They can become unrestricted free agents Saturday and reportedly are seeking contracts for a minimum of three years. Thornton, who turns 38 on Sunday, wants to return to San Jose if Marleau does. Marleau turns 38 on Sept. 15.
Sharks general manager Doug Wilson hasn't confirmed a commitment to bring either or both back.
"We have great respect for them," Wilson said after the 2017 NHL Draft in Chicago on Saturday. "They're cornerstones of our franchise and how we treat them and the respect we have for them is off the charts. We value them and appreciate them. Under a cap system you have to sometimes make tough decisions."
It's possible they each return to San Jose, but they also could be a package deal going somewhere else. Each of them reportedly has heard from the Los Angeles Kings, Nashville Predators, New York Rangers and Toronto Maple Leafs. There's probably more teams too.
Video: Hradek gives his 5 free agency storylines to watch
2. Andrei Markov and the Montreal Canadiens
Defenseman Andrei Markov, 38, wants to stay with the Montreal Canadiens and all indications are they'd like to keep him. The question is cost and term. Markov, who has played his entire 16-season NHL career in Montreal, reportedly wants a two-year contract in the neighborhood of $12 million.
In an ideal world the Canadiens would be able to sign Markov to a one-year contract, but they may not have a choice but to meet his reported demand.
Montreal's defense is thin, especially on the left side, where they have a plethora of third-pair lefties in David Schlemko, Jordie Benn and Brandon Davidson. Markov knows the Canadiens need help on the left side and also likely knows he can get a multiyear contract elsewhere.
3. More from Montreal
With no contract in place and a reportedly high asking price, it seems likely at this point that the Canadiens will let forward Alexander Radulov, 30, go to the market. Radulov, according to TSN, wants a long-term contract that will pay him approximately $7 million annually.
The Canadiens don't appear to be inclined to pay that much for Radulov when they also have to get Markov or another high-priced defenseman under contract, and either sign or trade forward Alex Galchenyuk, who can become a restricted free agent.
Markov and Galchenyuk could take up as much as $12 million of the $22 million in salary cap space the Canadiens currently have, according to CapFriendly.com. That leaves room for Radulov, but signing him would hurt the Canadiens' chances of filling out their depth.
Plus, Montreal still has to sign goalie Carey Price to a lucrative contract extension, which it can't do officially until Saturday.
4. Kevin Shattenkirk on his way somewhere
Defenseman Kevin Shattenkirk is expected to get a seven-year contract in the neighborhood of $42-49 million. Interest in him has reportedly come from the New Jersey Devils, Tampa Bay Lightning, Buffalo Sabres, New York Rangers, Toronto Maple Leafs and Boston Bruins.
The Devils make a lot of sense. They have the cap space and they have the need on the right side and the power play. Shattenkirk is from New Rochelle, N.Y., which is about 35 miles from Newark, N.J. He would instantly become the Devils' No. 1 defenseman.
Similarly, the Sabres make a lot of sense because they also have cap space even after taking on $5 million in a trade with the Minnesota Wild on Friday. They added forward Jason Pominville ($5.6 million) and defenseman Marco Scandella ($4.0 million) but traded forward Tyler Ennis ($4.6 million).
The Sabres have approximately $20 million in cap space, according to CapFriendly.com. They need to sign two goalies and defenseman Nathan Beaulieu, who can become an restricted free agent on July 1, but that wouldn't stop them from adding Shattenkirk to the right side of their defense, where he would join Rasmus Ristolainen and Zach Bogosian.
Buffalo had the best power play in the NHL last season at 24.5 percent. Shattenkirk would make it better.
The Lightning also make sense in that they have the cap space and a significant need on their defense, especially with Jason Garrison going to the Vegas Golden Knights in the 2017 NHL Expansion Draft. But they could be looking at a lower-priced option such as Karl Alzner, Trevor Daley, Dmitry Kulikov, Michael Stone, Dan Girardi and Ron Hainsey.
Video: WSH@PIT, Gm3: Shattenkirk nets PPG for OT win
5. Time for some mega extensions
Edmonton Oilers captain Connor McDavid is getting ready to sign an eight-year contract extension that will pay him $13.25 million annually, according to Sportsnet. McDavid, who still has one season remaining on his three-year entry-level contract, can't sign the extension until Saturday.
The same scenario is true for Price and New York Islanders captain John Tavares. They both have one year remaining on their contracts before they'd be eligible to become unrestricted free agents. They can't sign until Saturday.
Priority No. 1 for the Canadiens and Islanders is to get contract extensions done with Price and Tavares, respectively. The Oilers want to get McDavid signed so they can turn their attention to center Leon Draisaitl, who is set to become a restricted free agent.
6. The Rangers and the need for centers
The Rangers traded Derek Stepan to the Arizona Coyotes and lost Oscar Lindberg to the Golden Knights in the NHL Expansion Draft. That means they have to replace two of their top four centers from last season.
They likely are going to the market to find a center to replace Stepan. Potential options include Nick Bonino from the Pittsburgh Penguins, Martin Hanzal from the Minnesota Wild, Sam Gagner from the Columbus Blue Jackets and Thornton.
The Rangers could try to replace Lindberg with an in-house candidate, unless they wanted to try to bring back Brian Boyle, who finished this season with the Maple Leafs.
7. Goalies galore
The Philadelphia Flyers need a No. 1 goalie, or at least someone they can pair with either Anthony Stolarz or Michal Neuvirth. The Vancouver Canucks need a No. 1 too, unless they believe Jacob Markstrom can handle the load. And the Buffalo Sabres do not have an NHL goalie currently under contract, though Robin Lehner is set to become a restricted free agent.
Beyond the Flyers, Canucks and Sabres, the Anaheim Ducks, Maple Leafs, Rangers, Penguins and Colorado Avalanche need backup goalies.
The good news is the free-agent goalie market is expected to be deep, with Ryan Miller, Brian Elliott, Jonathan Bernier, Steve Mason, Anders Nilsson, Ondrej Pavelec and Darcy Kuemper all available.
The market is a little all over the place too.
Anton Forsberg signed a two-year, $1.5 million contract with the Chicago Blackhawks. Mike Condon signed a three-year, $7.2 million contract to stay with the Ottawa Senators. Keith Kinkaid signed a two-year, $2.5 million contract to stay with the Devils.
Video: EDM@VAN: Miller swallows up McDavid's backhander
8. What will Vegas do?
The Golden Knights are trying to clear roster spots and cap space, especially on defense, where they have 10 NHL players under contract and two more, Griffin Reinhart and Nate Schmidt, set to become restricted free agents.
The Golden Knights are heavy in the trade market and could help other teams fill a need that they might not feel is available to them in free agency. All 10 of Vegas' defensemen under contract are signed for one more season, which makes them even more appealing with the potential of a short-term gain without the risk of a long-term commitment.
9. Does anyone want Jaromir Jagr?
Jaromir Jagr, the second all-time leading scorer in the NHL, drew some laughs on social media Thursday with his tweets about how no GM has called or shown an interest in him as of yet.
It was funny and brought levity to an always tense time in the NHL, but it also brought up the question: Is Jagr going to get a job in the NHL?
He's 45 and has stated a desire to play until he's 50. Jagr hardly is done. He had 46 points (16 goals, 30 assists) in 82 games with the Florida Panthers this season. It was a 20-point dropoff from his 2015-16 total, but he still was fourth on the Panthers in goals, assists and points.
If Jagr can't find an NHL job he'd likely play in his native Czech Republic, but odds are he'll get a call eventually, if he hasn't already after his pleading on social media.
10. What about Jarome Iginla and Shane Doan?
In addition to Jagr, veteran right wings Jarome Iginla and Shane Doan could be looking to play another season. But who is biting? It's not clear.
Iginla scored 14 goals in 80 games with the Avalanche and Kings. It was his lowest goal output in a non-lockout shortened season since he scored 13 in 70 games with the Calgary Flames in 1997-98, his second season in the NHL. He celebrates his 40th birthday on Saturday.
A return to the Flames would be a dream scenario, but could Iginla go back there and be a role player? Would they want a 40-year-old player on a young roster that could be ready to win now?
Doan will not return to the Arizona Coyotes after 21 seasons in which he played 1,540 games and scored 402 goals with the organization. It's not clear if he's going to play again since he's so deeply rooted in Arizona and would have to move his family to continue his career. He'll be 41 on Oct. 10.
If Jagr, Iginla and Doan continue to play in the NHL expect it to be on one-year contracts. Iginla and Doan have not won the Stanley Cup so that is something they could be chasing. Jagr hasn't won it since 1992, when he won it for a second time with the Penguins.