Love to Barzagli in Juve shirt - I have no doubt in my mind that he will be a best defender in the world sometime in his career. He has physical, mental and technical capacity to be successful. Just looking around the teams, despite our relegation, I can't see any team being equal par with Juve in terms of attraction beside Milan and Inter. Ok not this year, but once we get up in Serie A, imagine the lusture of being part of rebuilding project of top 3-5 team in Europe should be mouth watering prospect for any professional football player.
The key IMO as Giovanetto said, whether Barzagli will move to bigger team in January. Milan will need a center back to partner Nesta given that you can't expect Maldini to be injury free at his age and Stam gone.
Inter will probably not want a player of Barzagli's price and wage give than they already hold expensive defenders in Cordova and Samuel. They will probably buy high risk, but high return type to groom for the future.
Roma, Lazio et al just doesnt have the financial muscle to trouble Palermo, which leaves Fiorentina, Milan and Juve as only viable option IMO if you preclude foreign venture like Real.
Now that Milan doesnt really have a history of adding a high profile player in January but Fiorentina has shown to be aggresive two scenario I can think of is (1) Milan buy Barzagli just before the transfer deadline (most likely IMO) & (2) Fiorentina go aggresive if they are in hunt for CL place and Palermo is out of the race. Now as a Juve fan, I hope (1) Milan get knocked out of CL preliminary round, which means they will less aggressive in the transfer window and (2) both Fiorentina and Palermo finds themself out of CL race.
If these happen I think Juve have a shout.