I think Partey has been very good this season, in part because Arteta has managed his minutes better. He's not as good defensively as he used to be, and makes an incredibly lazy pass or two per game, but his ability to turn out of pressure and break the press is still top class.
This said, in between getting old and moral turpitude, I'm happy to let him go.
Zubimendi looks to be the best available replacement.
I would offer Jorginho another one-year contract. He's mostly an assistant coach, and very valuable at that.