In my opinion, Xavi's job was good to bring Barcelona to finish in the 2nd standings, it means that things are getting better for now, so the final match with Villarreal even if they lose will still be good for Xavi.
I agree with you Xavi will be more prepared for next season, by starting a new career the squad will be shown to remain impressive and next season they will still be able to compete in the UCL with manager Xavi.
Xavi's Barcelona is not bad, much better than the previous coach. I feel this season Xavi has brought back good form for the Barcelona game, which is good because he doesn't have a lot of quality players in his team. Many young players have become Xavi's first choice this season, including Pedri and Gavi and several others. He maximized the potential of every player and amazingly he also managed to get Dembele to his good form this season which ended up being the top assist in Laliga.
There are good hopes for Barcelona next season regarding the title race. They will get some new players and throw some non-regular players this season. I think Xavi's presence at Barcelona as a coach makes Laliga even more interesting than in the previous Koeman era.