The book, which Mann cowrote, is part prequel, part sequel. There are really three stories. One is Hanna investigating a brutal gang of house burglars (I think it’s set in both timelines but could be wrong; is definitely post-movie at least in part). Then there’s what Val Kilmer’s character is up to post-movie. And finally, there’s a prequel element about McAuley and co. The three eventually overlap.
Unless they go down the line of digital de-ageing, it’s hard to see any of the original cast returning. Even the post-movie stories are set a few years after it, not now, though I guess it could be changed. But it’s hard to imagine Pacino playing a cop who’s still working, while Kilmer is sadly mute due to his throat cancer.
