We know that Paul Giamatti plays The Rhino in The Amazing Spider-Man 2, but we also know that his role is small, mostly confined to a James Bond-esque opening action sequence. We've known for a while that this new Spider-Man franchise was building towards the Sinister Six - a team of Spidey's deadliest villains - and the assumption was that Giamatti would return in a future film to be a part of that team. At least some of that statement is correct: Giamatti has confirmed he's back for Amazing Spider-Man 3.
I think I’m only doing the next movie, I don’t think I’m in the next-next movie," he told Collider while doing press for Parkland. So does that mean the Sinister Six are in the next film only? Or that The Rhino doesn't make the cut of the final team in The Amazing Spider-Man 4 (which Sony has already given a release date)? Who knows. He isn't even sure that he's not in 4. Those negotiations could still happen.
Also returning for the next film: dismal screenwriting team of Roberto Orci and Alex Kurtzman. They wrote the new film (and Star Trek Into Darkness and Transformers 2 and a bunch of other bad movies), and everybody liked their style - transcribing for the filmmaker's worst impulses - enough that they're back for another go-round. I have heard the script for Amazing Spider-Man 2 is actually quite good, so maybe they've been getting good dictation from Marc Webb.