An expansion of the stadium too around 65000 is not feasible unless a Metro station is built near the Stadium, at the moment it's a hassle to get to the stadium via public transport, eventhough you can take a shuttle on match day...
Anyways i dont think that Juventus will even think of an extention until the Continassa is completed...
Now if Italy were to get Euro 2024 that would be something else ( dont know if they are even gonna bid)