For their defense and midfield there are several players who are not really used much but Xavi still keeps and even holds back if a club wants to buy these players and now they are trying to return to looking for free players but there is still no expression of wanting to release several players who don't used even though this is clearly an obstacle to Barcelona's financial condition.
I also think that Barcelona really should think about getting rid of some of the players because first of all Barcelona does not have too much money right now in the bank. If they can get rid of some players whom they do not need, then I am sure that it will be a boon for their financial situation if they are able to do that.
And another thing is that players might be able to have a better future somewhere else by having a better amount of playtime. We have seen Barcelona defend well throughout the season, except in the match against Real Madrid. The defense of Barcelona was not convincing against Real Madrid at all. Barcelona cannot afford to do that if they want to win the La Liga title.
There are too many players in the team. These players also bring financial burdens. As you said, Xavi needs to give up some players. After Pique, it's hard for them to find a player like him on defense. We still have a chance to see a stellar transfer to the defence. I think star transfer is necessary. Because the Barcelona defense was always made up of star players.