Juventus without or without Motta can't change anything by just using a new coach because Motta can't do miracles in Juventus.
We don't know what Thiago Motta will do next season so we shouldn't doubt it before seeing how Juventus will perform next season. Seeing that the coach was able to make Bologna look impressive last season is proof that the coach is quite influential in Serie A. Bologna and Juventus are clearly different In terms of players, Bologna doesn't have great players like Juventus, but Motta was able to do well. Bologna was able to finish in a pretty good place and get a UCL ticket.
In my opinion, playing in the Champions League will provide big benefits for Juventus financially, so that Juventus management can slowly build the depth of the squad to be more even.
It depends on Juventus' performance in the Champions League, if he is able to get past the group stage he will get an advantage playing there so he can use that advantage to build their squad which is almost weakened. Juventus has experienced so many difficulties in the last few seasons that I didn't expect the most successful club in Serie A to experience so many problems that it almost made the club fall so deep.