I can't possibly think of any positive in letting Xhaka and Partey leave in the same season. If depleting a midfield that almost won the league is not stupidity, I don't know what is. I have said it before, Arsenal should delay that Partey deal till January. You can't be making one step forward two steps backward. Arsenal will be involve in a lot of competition next season, they need every player to be available, Partey Jorginhno and Rice are good players to help them stay ahead in the coming season.
They cannot keep all of them, even if they want to, they have to sell some of their players to make money from them and to get them off their payroll. Arsenal signed Rice for a lot of money so they have to make money from selling players in order to balance their books. Having said that, with the arrival of Rice, playing time for Partey will also be reduced, thus the player himself would wish to go. Overall Arsenal are doing good business in the transfer window this summer and it will help them to be in contention for the EPL.