I think it's inevitable that he is gone, it's just a question of whether it's this summer, or whether they get a chance to build around him for another 2 or so seasons before trade talks heat up again.
They don't have the pieces to get him now. They have one of the worst prospect pools in the league. Most of their desirable NHL played have NMCs. When he hits free agency in 3 years, Matthew could be on the decline as an impact player, and the Panthers with the current state of their roster could potentially be looking at retooling or rebuilding.
I'm not saying it's impossible for them to be like Boston and remain a perpetual contender well beyond the time people expect, but I think it's more than likely that they begin to decline due to ageing stars and a weak prospect pool.
The Rangers have all the pieces to make this work. They have prospects in Perrault and Othmann, a few young NHL D, and they have Lafreniere who while he has struggled to get to the next level with the Rangers would be a big name addition in this market.
They also could probably take Norris which might be a plus to Ottawa if a veteran is coming back in his place.