It is difficult to believe that Xavi could coach Barcelona. Nevertheless, that will not be soon for various reasons. In fact, his intention is to continue living in Qatar for a while.
At least until the 2022 World Cup according to 'Mundo Deportivo'. He will start coaching there for a few years to gain experience.
After that, it seems Xavi will move to Europe to start coaching bigger teams. He may go straight to Barca or he could go to some other teams first.
So the rumours which say that he could be the man to replace Ernesto Valverde are baseless.