You know, this whole idea of Sparda and Vergil being dead bothers me. In the DMC universe, isn't there this idea that souls live on, somehow? That being 'dead' or defeated doesn't mean you're completely out of the picture? It's a bit confusing how Eva is dead, for example, yet Mundus is able to create a copy in her image, which Dante treats (toward the end) almost as if she is reincarnated in Trish? That when powerful demons are defeated, their souls live on in weapons or their power can be absorbed by others ("take my soul and go forth") rather than being absolutely destroyed? And of course the whole idea of an Underworld or Hell filled with demons borrows from modern religions, most of which state that bodies are material vessels for souls that are immortal, and DMC is full of references to that kind of thing.
In that case, Eva, though dead, would have a soul floating around somewhere, as would Sparda and Vergil. They wouldn't simply be 'gone', right? Unless someone like Mundus has the power to completely annihilate a soul along with its body (Griffon? Eva? Vergil?)
In the DMC universe, souls should be around for ever unless they are deliberately destroyed... so I have this idea that if Sparda died a natural death, surely he'd be watching from... somewhere?