Not only Nero. I'm guessing (and hoping) that DmCs story will be consistent. That if there would be a DmC2 it would be the continuation of DmC1, not the last game in 4 DmC games. A bit like Assassin's Creed games seem to be doing. Each game has a story of its own, yet still pushes the major story a bit and reveals some stuff, so that when the final game comes, (hopefully) every question will be answered. As awesome as DMC is, the many unanswered questions that each game give us do not do it justice. And DMC4 was the worst in that regard. It only showered us with more questions about the DMC world. Hell, even the story of the game itself (and not the story of the whole DMC project) isn't complete thanks to Nero's existence.