This year:
Raki & Vidal for sure, even for free. Same for Umtiti though it is more difficult.
Semedo if right offer comes, unless he accept reasonable wage. He is athletic player and I no need to give him another big contract while he might end up being next Umtiti after first injury.
Griezmann if 70M+ offer comes.
Coutinho even for loan.
Summer 2021:
-Whoever have not left from previous list
-Suarez
-One of Pique/Busquets
-Braithwaite
-Arthur if he continue without development
Summer 2022:
-Alba + any player not named Messi who is born before 1992
Edit: I forgot that Dembele is still here, should leave by next season at most
rakitić,dembele,umtiti,greasemann,rafinha,firpo for start. suarez,busquets,pique,alba phased out for next season. i'd keep coutinho because no one will pay more than 50-60m now and loaning 120m signing is just so dumb