I think 3-5-2 is perfect for juve. Alves wouldn't mind - he's always in attack mode anyway. pjanic is a very versatile player so I don't see a problem there.
Sanchez will never happen so no reason to talk about it. If it was up to me I'd go with 3-5-2 at least until barzagli will retire. our defensive line is so good it will allow the attackers more freedom - especially from the flanks. Alves and Sandro will demolish everyone.