The truth is if Xavi leaves, all the potential replacements mooted so far are far less suited to managing this crop of youngsters that Xavi himself has brought through, than Xavi himself
Indeed there is a big chance the next manager comes in and destroys all the good work Xavi has done with the youth. They might not have seen him in his prime, but that level of respect will have been evident within the club and you can see that with the way they interact with him.
The only managers that could probably continue this feel good factor and upswing in performance are Klopp and Motta. And for next season at least, we have zero chance of getting either. Worrying times.