Large possibilities for Bayern Munich signing Xavi Hernandez after last confirmed he will leave Barcelona indeed winning the UEFA Champion League tittle in this season, his decision have been final for leaving Barcelona and great opportunity for Bayern if can't sign Xabi Alonso as their first sign priority. I don't think bad with both manager have good reputation right now and success bring their previous teams have quit well performance and waiting which one both of them are large chance for signing.
Xavi Hernandez will be easily manager for signing by bayern Munich because he will be free agent next season, for Alonso seems bit difficult he still has contract left with Leverkusen and many top teams such as Liverpool and Barcelona are interesting with Xabi Alonso.
I have not found any related news about this because seeing from the current situation after Xavi decided to give up his position at Barcelona next season there has been no further news about the future he will do including the club he will coach later because it seems that even if this is the end of Barcelona but most likely Xavi will also not go too far especially since the Bundesliga is a new place that requires more adaptation for him.
In addition, for Bayern at this time it is indeed possible for them to sack Tuchel after these 2 seasons have not really gone according to Bayern's will but there are still several other coaches who have also been linked with Bayern to date including Xabi who has always been in the hot news of several clubs who began to interest him because of his outstanding performance at Leverkusen in the last 2 seasons.
I think for next season there will be many unexpected events in terms of coaches and players in the transfer saga that occurs.