Well we still own the IP of course, but I'm not quite sure how it would work with MS being the publisher of Evo/HD and Fusion being out on PS4 as well.
Here's my thoughts about Evo and HD levels in Fusion: The way I see it, it wouldn't really make anyone super happy. The nostalgia value would be lost on the new players who's first Trials game was Fusion. Evo and HD levels look really bare bones compared to Fusion with lacking detail, animation and overall theme.
For example: The Evo team didn't have the animation tool in the editor until the end of the project so a lot of those tracks don't have animations at all, or they have animations that we're quickly added in. That WOTN ending with the squirrels, that was done with the physics tools by CannibalShogun, no animations.
Then there are the old fans who like Evo/HD over Fusion. The classic tracks wouldn't be as enjoyed because they would of course enjoy the originals over the remade ones.
In general I think there are a lot of things that people don't think when they want remakes/ports/HD editions. A lot of the times the gaming experience is not only tied to the game, but also the time that it was played. I've said this on the forums before, Evo and HD came out just in the right time when XBL was booming with action and a lot of people found out how fun Trials is to play for the first time and the community exploded with creativity. I sometimes go back to my old favorite games and replay them only to realize that the game (usually) is as good as I remember, but the memories that I have are also tied to the time when I played it and other stuff that was happening in my life. The game might be 1:1 port, but I've changed, learned new things and played other games that have changed my opinions on what's fun or good. Nostalgia is fun sometimes, but I think it also that too much nostalgia or the pursuit of that nostalgic feeling can prevent us from experiencing something new with an open mind.
This is just of course my personal feelings about the subject matter :)