I think it's possible that Arsenal may hold on to Sanchez. Unlikely perhaps but will depend on Wenger's reading of Sanchez's and his players mentality. How would Arsenal repalce Sanchez's goals and assists next season. if they let him go, they are in difficulties. If they keep him, they are also in difficulties because his heart wont be in it. Perhaps key is Arsenal getting someone in like Mahrez. Also depends on how much Sanchez wants to play for Pep. he could force it if he really wants. Easiest option is Sanchez does nothing and just lets it play out, but is he that kind of character?100%.
Also all the talk that Arsenal are gonna let him walk on a free is manifestly nonsense. Zero chance that happens for a myriad of reasons. Another transfer that's becoming more inevitable with each passing day. Football is a small pond and the signing of Lacazette has left City feeling even more emboldened that the Sanchez deal will get done.