At least half the league would be interested in Matthews even if he hasn't turned up in playoffs. So many GMs think they can be the genius to get the best out of players who underperformed elsewhere.
Teams that need a 1C desperately:
Utah, Seattle, Boston, Anaheim, Calgary, Philadelphia, Nashville.
Teams that could do with a 1C upgrade:
Washington, Buffalo, Rangers, Columbus, Chicago, Vancouver, Minnesota.
And then there is a list of teams who need some more firepower to take them to the next stage (LA, St Louis, Detroit, Islanders).
The market would be there if he's willing to move to one of several teams.