I personally prefer Arsenal to keep Thomas Partey and Granit Xhaka. But it seems that Arteta really wants to make big changes to the Arsenal club. Even though what I expect from Arsenal is to keep the existing players and add a few players to the attack line. As for the midfield, I think the two players actually played quite an important role last season. But Arteta seems to have a strong desire to bring in Declan Rice. Even though the first offer was rejected by West Ham. but it seems Arsenal have not given up.
I think Arteta had other plans and his decision to change players was inevitable. However, in the future, Arteta will definitely know what Arsenal really need. Even though I actually don't agree if Xhaka is on the sales list, it's not too much of a problem for Partey because his performance also declined at the end of last season.
However, Chelsea has talented players like Aubameyang, Pulisic, Sterling, and Fofana in attack. So if Chelsea's new coach Pochettino can't strengthen the bond between the players, this team will not be able to perform well in the next season. Pochettino will have to work hard to strengthen this squad.
The coach doesn't need to strengthen any bond between those players you mentioned as alot of them will be sold or loaned before the transfer window ends. Already Aubameyang is going to continue his football at Saudi Arabia and other Chelsea players will be following him out of the door. Fofana would be sold or loan as there are rumors of Chelsea wanting to sign a striker who isn't going to be our first choice striker which means we'll likely get two strikers coming in before the window closes. Pulisic who be sold as well. Sterling still has some quality in him and can be utilized very well under Pochettino and that's the only player available frolm your list.
Fofana and Aubameyang don't seem to need to be strengthened or defended by Chelsea. Whatever the new coach wants must be completely endorsed and a complete overhaul must be made so that it doesn't look like Pochettino half measures. Thus there is no reason for next season to target the final ranking in the standings.