We have absolutely no idea
Things that look certain for now are :
1. The return of Giovinco and possibly 2 more youngsters (Marchisio and De Ceglie)
2. Purchasing another striker (Amauri the name being mentioned the most)
3. Mellberg is already ours
Everything else is pure speculation. Flamini's name is mentioned a lot but i don't know how much truth there is in the rumours.
Obviously Juve will need 1 or 2 more new defenders, apart from Mellberg.
If we buy Flamini that, and the return of Giovinco+Marchisio, may be it for the midfield.
Personally, i expect one or two surprise signings.