Why won't Evans be affordable next year. The fact that he's 29 works against him, when he was 26 and coming off 13 goals and 29 points in 72 games as a sophmore he was getting paid in part because of his potential. Now at 29 where he still hasn't hit 30 points, his goal scoring is only half of what it was back then there's little chance he'd get any kind of significant raise even as a UFA.
As to whether there's room for him, it's too early to tell right now. We really don't know how long most of those guys will take to be NHL ready, and odds are high at least some probably never will be.