For now, DMC is goin' down hill because it's starting to lack motivation for characters. The only thing Capcom has going on for them right now the curiousity surrounding Nero and Berial's "You were just like him" comment and not to mention Yamato being resurrected. Unless they can pull something extremely well off in the next edition for fans to scream for more action, it will end up being just a dud. DMC 3 to me was deep in the storyline. DMC 1 was deep in emotions. Unless they can somehow pull these off in DMC 5, the game will just lack interesting conversations, not to mention turn fans off from all the adrenaline rushing through their veins to get to the next level.
I think there is more to it than meets the eye with Dante's behaviour. Sure he didn't bat an eyelash but who's to say he isn't interested though? Nero is a teenager with demonic arm and have some sort of power...I have a feeling Dante knows something but he's not entirely sure. Dante even said Nero he is the same as him, but he's different from any other normal demon. The series hasn't offically ended yet, so there is still time. I'd really like to see the series continue for another good couple of games to try and fill in the majority of plot holes. surrounding Nero's being and Dante's reason for still killing demons for people that have the "Password". Last I remember he got his revenge on Mundus, is that not enough Dante though? What else is he after to help his avengence for his fallen family? Anyways, I want them to end the series on a good note, not a disappointing ending.
Off topic: Trish is a cunning and intelligent woman, she had to pretty much blackmail Dante to get him off his a** to go to Fortuna. She knew something was fishy and didn't like it, so she had to take the initiative to get info from the inside. Also, if you remember, Dante can refuse jobs he doesn't like...it doesn't mean he doesn't care about the end of the human realm, if it's not worth his attention it's not important. OUT OF SIGHT, OUT OF MIND, I'm thinking. Lady on the other hand, is just a greedy whore who takes all of Dante's money because he's apparently in debt. In DMC 3 she had a better persona than the one in DMC 4.