If Sanchez decides to leave the club, I don't think Chelsea will miss him. They already have solid goalkeeping options, and in the event of his departure,they could recall kepa arrizabalaga from his loan spell at Bournemouth. Chelsea has young goalkeeping prospects, Djordje Petrovic, who could step up if needed.
The best players even though missed at replaceable, it might not be so soon but it'll definitely happen. I don't know why we see too much focus on the goalkeeper thriving when they should be talking about the defenders. As much as I'm concerned, Chelsea needs a Thiago Silva who can read the game and arrange that defenders until that is that, they'll continue blaming goalkeepers unnecessarily. Kepa and Petrovic are going to be axed during the next transfer window.