Well, I think it will be a good deal. I like Dybala a lot, I see huge potential in him, but he is not irreplaceable. Upfront only Higuain is kind of irreplaceable, because you can't find a striker who will score so consistently 30+ goals every season for less than 100 mil right now.
Dybala on the other hand must prove himself as World class. So far he has proved a lot, but he is not on the same level as the World class forward players and there is always the possibility, that he'll never be. I would love for him to stay for a long, long time, but right now if we sell him, we'll get an explosive winger, who'll be pretty useful for us too. Juve, actually, can win a lot from his transfer.