Barcelona won the King's and League titles in the season, but the defeat of the Champions League means that this season has basically ended, the only task is to be able to complete the season with unbeaten record!
I think Barcelona needs to sit down and release few players and then recruit some, honestly it's very difficult whom should they release all are so good but hard decisions will be made sooner than we think and messi is the guy who's calling all the shots.
It's not that difficult to guess who's going to leave the team at the end of season. Off the top of my head: Denis Suárez, André Gomes, Aleix Vidal, and Paco Alcácer, these players just don't have the level to play in Barcelona, I think at least two of them will leave the team. Dembélé could leave on loan but only if they sign Griezmann. Tbh, Barcelona needs to sign a few quality players if they want to compete in the Champions League again.