For next season, this current Barca squad needs: No new players. Some of the underused players will leave, like every year. Promoting Alena will backfill one of those spots, so that he can get his chance to rust on the Barca bench. It might be better to have a smaller squad next season, I think even 20 players could be enough. Atletico is going with 19 as of now. Some of the players outside of the first 11 could back up additional positions. For instance, Gomes could backup at RB if Semedo leaves. If Semedo stays, S. Roberto could actually play significant minutes in midfield.
On the back line, going from Semedo or Mina to someone who could cover multiple positions would be a plus. Or, could Mina or Pique backup as striker? I think Digne might be able to cover the 4th choice CB job. I'd be fine if all three of Paulinho, Gomes and Vidal continue on next year. The front line alternatives to just always Messi and Suarez have now proven themselves: Coutinho on the left, Dembele on the right, always play 4-3-3 when either Messi or Suarez are not on the field. No new forward is needed, maybe just one newbie to squander as deep depth.
On the back line, going from Semedo or Mina to someone who could cover multiple positions would be a plus. Or, could Mina or Pique backup as striker? I think Digne might be able to cover the 4th choice CB job. I'd be fine if all three of Paulinho, Gomes and Vidal continue on next year. The front line alternatives to just always Messi and Suarez have now proven themselves: Coutinho on the left, Dembele on the right, always play 4-3-3 when either Messi or Suarez are not on the field. No new forward is needed, maybe just one newbie to squander as deep depth.