For how long though? It's just delaying the inevitable.
Also, Belotti has said nothing about wanting to leave.
Dybala contracts run till 2022 iirc ? you can keep him till 2020 and still sell him for tons of money.
Even if next summer he comes out and says he wants to leave, don't sell him and he make him respect his contract. He will still play, he will still be ready come start of the season. How many players wants to leave and ends up staying in their teams don't perform the next season, not many i'am sure. They are still professional players that wants to play, be called to their national teams especially when they are young, in their prime. You know very well that all the high profile we sold were by mutual decision, maybe they wanted to leave but we were very motivated to sell them too. None of them would've complained, refused to play, underperformed if we decided to keep them.