So far he's definitely upgradeable and if they find a viable option that makes sense there's no reason why they shouldn't pull the trigger. That concept applies to all but a few clubs in Europe though.
I think they'd be mental to do that. It was a disaster of a job and he's done a really good job rejuvenating the squad and putting together a young side, I think other than Aubameyang and Lacazette everyone playing today was 24 or under.