Real Madrid, Atletico Madrid and Girona are the only opposing club that seems to be hurdles for Barcelona next season, perhaps La Liga is going to be really interesting and competitive. Barcelona new coach, Hansi Flick did better with Bayern Munich although things didn't end well for him. Moving to Barcelona means more opportunities for him and he's one of the sincere coaches that will live up to the expectations of the fans. Barcelona trusts him to deliver an excellent job for the club which I'm pretty sure he will without any atom of hesitation or doubt.
Overall Hansi Flick's performance will really be seen by everyone next season while coaching Barcelona even though the coach has had a good performance with his old team in the past. However, next season Hansi Flick will handle a more different season with a more competitive team because remembering that the current rivals are also quite strong rivals in La Liga as you said. But what still concerns the Barcelona fans themselves is not the coach, but the players themselves who must be better because Barcelona needs to compete at the front quite consistently next season.