I don't think Juventus replacing Thiago Motta with Xavi would be an upgrade. If Juventus wants to reclaim their crown back in Serie A, they need a coach with a proven track record of success, someone that is capable of improving both their performance level and their style of playz While Xavi might be under consideration, I don't believe he possesses the tactical ability and experience to achieve such a feat especially given the highly competitive nature of Serie A.
It is too soon actually for now if Juventus try to replace Motta with Xavi because after all for now he still needs habituation and it is unlikely that optimal results can be produced for the first season at Juventus at this time.
Maybe it can happen but not all can be like that and I think Motta is also still pretty good until now when it comes to performance even though their matches ended in draws (13 draws 13 wins and 1 loss) but the fact that Juventus is one of the clubs that can't even lose is unusual compared to before.
At least give confidence until the end of the season if Juventus really want to give freedom because replacing in the middle of the season can actually make the situation worse in the end in terms of performance.