I would love it if Capcom would come out with a Devil May Cry game that's unrelated to the core series of games, but has all of the important characters including some of the larger bosses.
It'd still have to be hack'n'slash, but make a two player arena-type fighting game. Not saying it'd be a super huge seller, but still, imagine getting to pick your favorite DMC character from any of the games off of a roster, being placed in some random arena, and then fight another character one on one.
Imagine some of the sweet battles that could happen. That game would answer every what-if battle ever. Dante vs Credo, Nero vs Vergil....Credo vs Nelo XD...Trish vs Lady >>...Phantom vs Griffin (yes...I seriously meant the boss thing)