It makes sense what you are saying, but Inter's style of play is heavily dependent on a goalkeeper whom is good with the ball on his feet. I mean, someone who is following Inter (non-Inter fans, because Interisti already know this), will realize how crucial goalkeeper is to Inter's game. We tend to involve our gk a lot on ball possession and eventually switch sides, through passes in the middle or even long passes forward. These small details matter a lot in our game, and a goalkeeper like Donnarumma doesn't exactly fit, but an exception could be made (in case of a massive paycut) for gk of Gigio's calibre.
I mean, he's only 25 years old. If he's willing to evolve his game, pretty sure he could make a progress. Not saying he's gonna be Onana or Ederson, but definitely he could improve his ability with the ball on his feet.