If Arsenal were better managed they'd sell Sanchez now, and buy a young player like Sane or Jesus who can go on to be the next Sanchez.
Situation is different for City, we need a player for the here and now, but I would not be too upset if were to lose out on him. I watched Australia v Chile yesterday and apart from a couple of moments Australia effectively dealt with him. He was playing wide left, and because Australia needed to win by 2 clear goals they threw men forward exposing themselves to counter-attacks, and Sanchez of old would have had a field day. He really struggled to beat his man. There were a couple of moments of great quality, but overall he was getting very frustrated.