Personally, I think it would be a pretty good thing.
However, I don't think it should follow the traditional CV sort of way. I think it'd be wiser to recruit other hunters. One of the things I found strange is that, it gives off a there are many hunters and slayers, but the only one that ever shows up is one of the Belmont clan. It's one of the reason I like Dracula's Curse. It gives the lore a bit more than Belmont slays Dracula.
Sypha and Grant brings in the idea that there are other people who's out there that's capable. Alucard, adds a bit of dynamic to the evil side.
And they should put in permadeath for characters. That'd be awesome. Raises the bar of preserving your characters and not a we all survive type of ending that makes it sort of feel like it's not really a treacherous journey after all.
And of course, that'd add more to the game than just "invade this castle!"