I would guess that Barcelona having trouble right now is overestimated. First of all, last year they were the champions, they are literally the latest champions of the league, saying that they are not doing well is unreasonable, secondly they have one year right now where they are not the champions if they lose this season (when they lose it) so it is not a big deal.
On top of that, they are a team with a lot of financial trouble, so they managed to do the right thing and figured out a lot of great young players, they have 6-7 great young players that can play amazingly and I believe that they should be doing fine. I think the best thing to do in this case would be just considering them lucky and they can be doing better next season with what they have.
It depends on who will be Xavi's successor.
We know for now Barcelona still need a lot of things to do because apart from Xavi leaving next season there will be several more players who are certain to leave, especially for their loan players.
Although in the end we know that in Barcelona a lot of talented young players but this also depends on how the new coach brings them into the game scheme that will be done especially some of their current young players such as Gavi, Pedri or De Jong have fitness problems where injuries that take a long time to heal.