Aren't there licensing issues which never got resolved? Last gen, licensing issues prevented the Xbox version of MvC2 from supporting online. (Basically, Capcom no longer had the Marvel license. Although they could port the game to additional platforms, any changes to the game would violate the licensing agreement.)
Even without the licensing issues, 2D games with huge casts seem like a financially poor choice for HD Remixes. A large part of what made the original versions of those games financially viable was the ability to re-use old sprites. If they had to redraw all those sprites from scratch, the costs would be enormous.
All that said, I'd love to see it happen.