The major issues for flick would be the fact that Barcelona themselves are almost entirely broke and for a club like Barcelona that wants to return to their former glory they would definitely need to bring in some players and that would require funds which at the moment seems to be some of their issues but even at that I still expect them to be different atleast they have some good players, it just all boils down to the fact that a good coach with good mentality needs to handle the club.
Of course it will be a big obstacle for Flick in building a team without strong support from management to recruit quality players.
Barcelona management has said that they will build this team with the young players they have, of course this will be a problem for Flick especially as their rivals Real Madrid are now building a much stronger team with all the advantages they have.
However I still believe in the process that Barcelona will go through to build their squad so that it can return to its glory days, everything needs a process and Barcelona is going through it, we can see Barcelona's young players with quite good quality so it is indeed possible in In the next few seasons they will be able to shine.