From a realistic POV, I don't see how we'll upgrade our squad without selling one of Vidal or Pogba.
I love Pirlo, he's brilliant, but in Europe we'll get overrun IMO. He doesn't have the legs anymore, although he can still be very useful for Serie A.
For next season's CL I would like the following:
Buffon
Barzagli Bonucci Chiellini
Marchisio
Lichtsteiner Vidal Pogba Asamoah
Tevez Llorente
I know it looks weird, but its essentially a 3-5-2 but Marchisio to be used for defensive cover to allow Vidal and Pogba to be used effectively in attack.
I think Storari will leave after this season, Pirlo will most likely extend for a season or two, Lulic would be a good acquisition for the right price, Quag out, Vucinic out, Isla should stay if he's stays at the level he's been showing recently, Osvaldo likely to be redeemed.