For what it's worth, Marion isn't willing to speak publicly about his plans for the offseason, especially with the Mavericks facing an elimination game on Friday night. Per MacMahon: “I’m not looking at that right now. We’ll talk about that when it’s done.”
Marion—who made four All-Star teams as a member of the Phoenix Suns in the mid-'00s—came to Dallas in a four-team trade during the 2009 offseason. He then signed a five-year, $39.9 million deal. He was a critical part of the Mavericks' 2010-11 championship team, guarding such offensive dynamos as Kobe Bryant, Kevin Durant and LeBron James as Dallas steamrolled through the postseason on a miraculous run to the title. Dirk Nowitzki and Marion are the only Mavericks remaining from that team.
Yet again, Marion has shown his defensive versatility in these playoffs, guarding a wide range of Spurs, from power forward Tim Duncan to point guard Tony Parker.
While the Mavericks are interested in bringing back Marion, they'd expect the 35-year-old to come back at a reduced rate, per MacMahon: "…he’d have to take a significant pay cut from his $9.3 million salary to stay in Dallas as the Mavs attempt to rebuild a championship roster around Dirk Nowitzki."
Obviously, a player in his mid-30s isn't going to be worth what he was five years earlier. Per Basketball-Reference, Marion had a player efficiency rating of 16.0 in the season before he signed his 2009. That rating dropped to 13.7 this season.
But the Dallas front office will be playing a dangerous game with Marion. Clearly, they want Marion to stick around at a discount. But there could be other contending teams looking to make similar offers.
Marion did play one season for Pat Riley's Miami Heat. If President Riley comes calling again with an offer to replace Shane Battier as the Heat's defensive stopper alongside the Big Three, will he be able to pass it up?
Owner Mark Cuban will have to not only play up the familiarity factor—Marion has been playing in Dallas for the last five years, after all—but also convince the forward that the No. 8 seed Mavericks will be a much stronger contender in the immediate future.