A few things to consider:
Would Dybala get the touches he needs around the 18 on the right of Sarri's 433, or does Sarri prefer more of a wide man?
If Sarri would work with him, how will he link up with Ronaldo?
If we sign Icardi, would having Ronaldo - Icardi - Dybala have any chemistry?
I would rather keep Dybala as I think Allegri stifled him a bit, but including him for Pogba is very tempting. So if there are question marks for the questions above, then we might need to sell him unfortunately.