Sterling was gotten on Loan from Chelsea. The term was that if Arsenal loves his performance by summer, they will buy him but with the way things is i don't think Arsenal will want Sterling. He will be returned to Chelsea not minding the fact that he loves to play at Arsenal.
For the players who might be on the list for Arsenal to sell to raise fund i am suspecting Trossard (He also said he might want to leave the club), Jorginho; One of Arsenals best defensive midfielder but he has aged a little so Arsenal will be willing to let him go. Another player is Tierney, Thomas Partey and Fabio Vierra who was sent on loan to another club.
However, the Arsenal board will be blame if Arsenal don't win a title next season. I expect that aside from selling players to raise fund the club owners should give Arsenal enough funds to get players who will help win trophy.
I think the purpose of these possible transfers is so that Arteta has funds for further transfers this summer in the off-season. Arteta can't win the Premier League, they are constantly missing something, Arteta apparently thinks that the problem is with some players, that some positions require strengthening, but he spent a lot of money in previous seasons, apparently further funding will be impossible without selling some players that Arteta does not count on.