Change is needed in every competition but I think Barcelona doesn't need to make changes for now because I think their squad is perfect enough to compete next season, Hansi Flick just needs to maintain what he did last season, but maybe the small shortcomings that need to be fixed are on the defense side because even though their defense is not bad sometimes the players like to make mistakes that result in defeat.
Btw I haven't heard the latest news regarding the purchase of Nico, has Barcelona not found common ground with Athletic Bilbao?
Barcelona certainly has plenty of work to do before they can remain competitive the coming season. I will concur to this and say that all teams will be getting better and Barcelona should begin now. They are a team that can improve but it does need some work in certain areas, like defense. They are frustrating at times when the mistakes of their individual players actually end up costing them the matches, it is towards this end that I would suggest that they enhance their defensive department since they could be more consistent in defense perhaps by acquiring older more experienced players to assist them in the defensive department.
That is to say, at least Nico appears to be a little bit stagnant. They have talked about a potential transition but there is a tricky bout of negotiations between Athletic Bilbao. It is a tricky deal as Bilbao is considered to be not easy in negotiations and they will hardly be willing to almost push away an important player. In case of bringing in Nico or other good quality player, Barcelona will have to ensure good management of their finances alongside improving their squad. It might make them suffer next season because they are not doing the right things in the market.