Juventus has so many players who are over 30 years old. This needs to change immediately. They need to evolve into a more dynamic team to fight harder for Serie A titles. Football is changing and dynamic teams are one step ahead now.

Motta is a young manager which is a plus for Juventus about this topic. I wouldn't expect him to prefer old player signings much. His system would also be different from Allegri probably. But before anything else, they need new transfers like I said before. If they sign midfielders who can contribute much more to scoring, it isn't too difficult for them to stay in the title competition until the final moments.
That's correct.
A list of these names are Szczesny Wojciech, ( Who should be leaving soon ) Alex Sandro, Danilo and lastly Kostic.. They don't really have too much of them squad above 30 which is not bad. Thiago Motta has got good plans I believe, let's see how he shapes them next season, it's the right timing so he could get to know them well during pre-season. Winning the Seria A next season with this squad would be difficult no doubts but that will possible in the next few seasons ahead.
Younger managers are big deals right now. We can see how, Mikel Arteta, Cese Fabregas, Xabi Alonso and Xavi Hernandez are all dominating.
They're currently chasing for a swap deal with Manchester United between thr names Mason Greenwood and Chiesa. They will definitely make significant signatures.
Finally, I don't see Victor Oshime leaving this season no more.