It could happen. I've seen crazier video game crossovers, and considering the two of them are hack-n'-slash juggernauts, I don't see why Capcom and SEGA wouldn't collaborate like they've done before.
It would require DMC to drop all dignity and fall full-sweep into the over-the-top, nonsensical absurdity that characterizes the Bayonetta games, and since I'd like DMC to take a more serious approach to story in the next game...and possibly better writers, if Capcom can help it...having the crossover happen would definitely conflict with my aspirations of where I want the series to go.
Unless Bayonetta steps up to be more serious in tone, which I guarantee will NEVER happen.