Lets say Pirlo retires next season.
We would have Pogba, Marchisio, Vidal, Marrone, Asa, and Padoin as cm. The only players out of their that are kind of creative or have can make opportunities are Vidal, Pogba, Marchisio, Marrone. Even though we play a 3-5-2 mainly because of the defensive side of the formation and also the fact Bonucci has some nice passing, and it allows Pirlo more time and space when on the ball. But we wont have Pirlo and that is when I think we should ultimately switch formations and tactics. We can play a formation of a 4-3-1-2( which doesnt provide enough width), we could play a 4-2-3-1(which is probably one of the best formations) and we can play a 4-3-3. However we would obviously need some purchases. If we were to play a 4-3-1-2, we would probably need a lb(unless people are convinced of keeping asa there even though he played there maybe once last season), and a attacking midfielder or trequartista of some sort. The midfield would be comprised of Vidal-Pogba-Marchsio. If we were to switch to a 4-2-3-1 we would need a lb, and 2 wingers and possibly an attacking midfielder. It would probably be pogba-vidal as the holding midfielders and possibly marchisio as the attacking midfielder. If we switch to a 4-3-3 we need a rw and a lw, and also a lb.
We need 2-3 purchases if we do plan on playing a non-Pirlo dependent formation. I dont see the 3-5-2 working too well without the dpl. I would rather see a more advanced playmaker than continue to look for a vice Pirlo when there are non and you have to spend probably close to 30m for Veratti.