I think it's just too expensive, specially given if they force him to move this summer if he doesn't extend. Meaning it's fee + big salary.
Someone has to buy him for that to happen. And afford his demands. Does he even want to play abroad?
And let's see who needs a GK.
Barcelona will get ter-Stegen back, so not an option.
Bayern can afford him but I doubt he wants to move to Germany. And Neuer is staying, so it's not ideal.
Real Madrid probably won't replace Courtois, and I doubt Xabi Alonso would want a GK that's not readily able to play well with his feet.
Manchester City, Chelsea, Arsenal and Liverpool are not options.
Manchester United, if they win the Europa League, might consider going for him, but they'd still need to get rid of Onana. Will PSG accept him as part of the deal It's likely with Luis Enrique. But not so sure if he wants to move to England.
Juventus is not an option.
Napoli won't break the bank to bring him back home. I'm not sure if they're going to renew Meret or not, lost track of that episode.
Milan has Maignan and won't break the bank to bring back a player they labelled as a money grabber.
He wouldn't move to an Arab league. Or the MLS. At least I suspect he wouldn't.
It's very likely that he'll end up here. And tbh, I want him here in 2026. Mostly because we cannot afford to have him as a rival. Unless some other prodigy appears and we can swoop in. Donnarumma has 8-10 quality years ahead of him.