He should just take this offer and leave in my opinion. Because this season with Juventus wasn't good for him at all. The punishment they got made things even worse for Juventus. Otherwise they were at least going to be able to qualify for the Champions League. But with punishment or not it is still not the best season for Juventus that's for certain.

Juventus need to be competitive for the league title in the Serie A. It doesn't seem like Allegri can do this for now. Juventus need some additions to the squad as well but they should start their attempts for new players with a new manager.