There are speculations about Arsenal allowing Thomas Partey to leave this summer. Honestly I don't really have a problem with selling Partey at that amount. The problem is also selling Xhaka as well. It'll really leave their midfield lacking in experience though. In as much as I want him gone too but not on the back of losing two of their midfield generals at one go.
Remember that the midfield is at the heart of how they play. Even if the new guy comes in and hits the ground running, we can't realistically expect two new midfielders to hit it off immediately.
If it's just speculation it still doesn't look like there's a possibility of a move, but if Arsenal have to sell a player in their midfield to get a new player to replace him there's no problem as long as it suits Arteta I think it's fine, maybe Arteta wants something new for their squad team let alone facing a great club in the league as well as in the UCL next season.
It does take time to make the squad team solid, playing in rhythm according to the wishes of the coach and the strategy made, but I think over time if new players have had enough playing hours I think they will quickly adapt to other players, the competition is quite tight, I think I think Arteta just wants to create a new style of play to be able to win the league next season after his failure last season.