There were no contacts between Juventus and Xavi, and Motta is promised that he will remain as head coach next season, so it seems that everything suits them. Although I am also inclined to think that Motta is not the best coach for Juventus, in essence he is no different from Alegre, very similar manners and strategies, maybe the only difference is that Motta is younger and more reserved on the field and in transfer demands.
They can simply just fire Motta, and hire Xavi, that's how it works when a team makes a managerial change. I hate this fact, but if you give a 2+ year contract to a coach, and then they suck terribly at half part of the season and get fired, they still get paid for the 2+ years they were promised.
So in "theory", a manager could go get 2 years worth of contract from 3 teams, within a year, just get sacked by them. Start with one, get sacked, get another at the middle of the season, get sacked, and get hired by the third one, and get sacked at the end of the season. That way, he would have 6 years of money coming in, for just 1 year of work. Don't know if it happened to anyone with three clubs, but we have seen many with two clubs before. So many got paid 4 years for 1 year worth of work.