This is a problem I figured they'd run into. Eventhough this is a flagship series for Sony along with God of War, The Last of Us, and Horizon, i.e. something they'll want to continue making, unlike those games it can never really change at all. Spider-Man is always going to have to be Spider-Man in New York. It can be a different Spider person and a slightly bigger or different New York, but those parameters are always going to be there.
The Arkham games had the benefit of starting off in an asylum, then moving to a part of Gotham, and then the entirety of Gotham, but Spider-Man PS4 already gave us New York from the get-go, so settings wise there's very little to really expand on or change. The next Spider-Man game is undoubtedly going to be set in new York, and so will the one after that. Maybe we can get a Spider-Gwen game, but besides character swaps and graphical advancement I don't think there's much else this series can offer diffferently.