Vergil better get a campaign as well. It wouldn't be hard to just throw him into the levels that his moveset can complete since character select screens already exist.
Hopefully the women get playable characters too, but despite Trish being literally the best playable character they've ever made, Vergil needs that priority. If anything it's almost weird he isn't unlocked after you beat the game, if you ignore how much work that would have been.
The dream would be an alt campaign with the three of them taking the spots of the current three protags. Wouldn't need like, a plot, just make it so each character can complete the levels they're assigned to. Mayyyybe have a Dante final boss too but that'd be going the extra mile.