Yeah, no such thing as 'permanently,' in the long run. Bucky's back. Barry Allen's back. Everyone comes back, and the bigger their name (Superman, Wolverine, etc.) the faster it's going to happen.
My favorites on the X-side of things include Nightcrawler (who's died and come back), Cyclops (who's died and come back and died again) and Madrox (who's died and come back and died and is coming back even as we type). I'm sure that other favorites like Hellion and Dust and Unuscione and Frenzy will die and come back at some point (possibly after a decade or more of being dead, since they aren't exactly top tier). It's like a rite of passage for X-peeps.
Heck, even X-characters with such short runs and ancient pedigrees as Mimic and Unus the Untouchable got to come back (although either or both could be dead again, I have no idea...)!
As long as Jay Guthrie stays dead, 'cause screw that guy.