I would want them to add new characters but also show Neros progess & Dante and Vergil we could have seprate shares
I would like to see the humans rising up after the reveal of demons being real. Technological innovations, new weaponry, organisations dedicated to fighting demons, and also new cults rising up. Then in answer to this, I would like to see the demons step up their game in order to counter both the new human power and the twins being stuck in the Underworld. A new demon king rising up and taking the wheels of Hell would be cool, we could even have Mundus make a triomphant return.
My only problem with this is that the DMC series has a rather confused sense of what humans are capable of. In DMC5 we have the nameless military soldiers in Redgrave city being utterly trounced by demons but back in 3 we had Lady fending off countless demons by herself despite also merely using firearms. Even within 4 itself you had Dante admitting that humans are inferior physically to demons, but earlier when Nero meets the Order Knight (actually a demon possessing the empty armour) in Fortuna Castle he sees no problem with how a human supposedly made it past all those demons with only a spear and shield and is convinced the knight could handle himself. ¯\_(ツ)_/¯I would like to see the humans rising up after the reveal of demons being real. Technological innovations, new weaponry, organisations dedicated to fighting demons, and also new cults rising up.