I think that Tachi will be a great sub, or maybe with a little bit of luck can be a starter. The problem here is that Juve need to buy a world class midfielder in order to keep Buffon and the others so if this happens we will have :
Marchisio, Paro, Zanetti, Tachi and a World class midfielder.
I mean, 5 midfielders is too much and we will have to send on loan Paro or Marchisio.