I expect Barcelona to be different -more improved- in the coming 2021/2022 season, I hope they don't sell there young players, it was rumoured that Trincao is close to leaving to Leicester, I think Barcelona would be exciting even in the UEFA champions league, hopefully Ansu fati would avoid injuries and showcase himself, I still envision Messi going further in his season as a Barcelona player, in a summary Barcelona would be a bang.
They might have improvements or might not. It will depend on Messi decisions and transfer season. Even Messi stays in the club and they have good transfers, no guarantee that they can get success (with titles) in the first season with some new contracts. New players need time to build up connections with all squad. Some can have quick adaption and some will need one or two seasons.
Ansu Fati is a great player from La Massia and the first outstanding one after the generation of Messi, Iniesta, Fabregas, Valdes and Pique. The latest player who created such hype like Fati is Bojan Krkic who later has a failure in his career. I hope Fati will have a brighter and more successful career than Krkic.