That ending was really bittersweet, though I have mixed feelings on the story as a whole.
It's pretty obvious at this point that Dante and Vergil ain't ever gonna "die", but I still feel like that was an excuse for them to end the series right here - and even if we get a DMC6, I think that was Dante's swan song, between him getting a whole host of missions in this game, as well as having by far his craziest combat mechanics yet. I can see them never bringing the twins out from the underworld.
Guess it's the Nero show from now on. To be honest I'm not sure how to feel about the story yet, what I kinda liked about DMC4's narrative was that it was essentially a new story, whereas DMC5 feels like a greatest hits of the series' most iconic moments. I guess they covered their bases to make sure fans get what they'd want in case there isn't a sequel (confirm Nero's heritage, bring back Vergil, etc) so in that sense it's good to have some closure after 10 years. But at the same time it's hard to really get a sense of where the franchise is going.
Anyway the game was a lot of fun but I'm still not jiving very hard with V's play style and I feel like they really conveniently unwrote him from the entire game, both in terms of having a story payoff as well as not really having much in the way of a final boss. It was pretty obvious that V was Vergil (figured it out pretty much the second I used his taunt), and for a while I had the impression that they were gonna go for the angle that V's personality itself was holding Vergil back, like an internal conflict kinda thing, possibly even having some story bearing on why he ended up having a kid. But nah - V just wants to get back to Urizen and then Vergil is back to being Vergil, and it's like DMC3 never ended. Even his relationship to Nero is treated as basically "yeah whatever that happened".
It's probably why the story is still a mixed bag for me. I'm not sure how worth it was to relitigate a lot of plot elements that didn't entirely need spelling out. The better story moments imo involved anytime Dante and Nero interacted. I guess only time will tell.
But as for everything else, the game play is obviously aces - Nero and Dante are the best they've ever been, though I think the endgame stretch is really haphazard at times. Some more unique environments in the latter half would've been welcome. Nonetheless I look forward to replaying the game, especially since Nero actually has his DT now.