Difference is clear, but is one game we can field Dieo-Trez-Amauri. But if we'll sell Trez we can field Diego-Gio-Amauri, so Gio can play as support forward more often.
We'll have 5 players (Diego,Gio,DP,Amauri,IQ) for 3 positions, and no one from this 5 wont be a benchwarmer.
For some deep we can buy some young and promising forward who'll sit on the bench without problems, not like Trez. Or take this one from Primavera - there are Daud, Immobile, Esposito - all of them can get this chance.
At the end, we have to build new Juve. So we have to say goodbye for some our older players. Some sooner, some later, but it's life.
ps. With all my respect to Trez. He is a great forward, but maybe he have to leave Juve -that will be beter for him (gain place in starting XI) and for Juve.