I think the squad will be a bit thin for the first half of next season.
Alves will go, the team will not be willing to give him the multiple years and big bucks he can get elsewhere. Barca, to its credit, lets players out of contract in their 30s leave, except in very rare legendary cases such as Puyol or Xavi. Iniesta will be the next one of those. Adriano would be a fool to not insist on a transfer, given that Lucho rates him lower than any coach Adriano has ever had. Ter Stegen has zero chance of becoming #1 the way Bravo has been playing, for the sake of his career he should demand a transfer. My bet is Xavi retires.
Who on the current roster is ready to step up for a larger roll next year? My list would be Bartra and Rafinha. I'd add Adriano, but Lucho certainly disagrees. Maybe Samper could beat our Sergi Roberto for sub minutes behind Iniesta, Rak and Raf.
So, I think Barca will cut deals this summer for 2 big-time players, to join the squad in January. A midfielder and a RB. Pogba and Danilo. A condition of those deals should be holding them out of CL group stage, so Barca can use them in the knockouts. Barca can afford to spend serious money, this is a very rich club.