A 3-5-2 with Italy would have been suitable for Prandelli's Italy not the current one. For it to work you need two workhorse WBs that are very solid defensively and with massive lungs to stretch defenses so that CMs can then do the attacking work. It worked at Juve because we had a massive central midfield, Pirlo being super-creative and both Vidal and Pogba being capable of scoring a lot of goals. If the CMs are going to be De Rossi, Montolivo, Marchisio, Acquilani and the like then there will be very few creativity and fewer goals scored. There is no one creative like pirlo nor any goal scoring midfielders like Vidal or Pogba. The midfield is purely defensive. That is not to mention that at best he'll have one okayish wing back that does not even have massive lungs to storm forward and back like the Licht and Asa do.
Our 3-5-2 could have only been improved on either by having more offensive wingbacks or by having world class strikers upfront. Italy's quality upfront is equivalent to the Mirko-Matri combo at best unless Shaarawy or balotelli or immobile explodes (unlikely).
3-5-2 will make the azzuri very hard to beat but they will rarely if ever score any decent amount of goals.
Regardless of formation, Conte's hopes will rest on Balotelli, Shaarawy, Immobile and the likes becoming world class.