I think it will be a wise thing to go to a 3 men central mid but 4-3-3 means Dybala on the wing which I doubt will happen and 4-3-2-1 means we play with no wingers therefore D.Costa Keita and Bernardeschi who we are strongly linked with will be played in a central position which means D.Costa not playing in his best position IMO Keita is dangerous when cutting in from wide IMO - Only Bernardeschi remains as I believe he is good fit at central position
4-3-2-1 is the way to go if we change to 3 men midfield as I just cant see Dybala playing wide as he is a much better player when playing in a more central position
Juve should be able to play a 4-3-3 with Dybala moving centrally while the opposite winger stays wide. Much like with Messi's central movements, Alves can provide the width out right.
A 4-3-2-1 is possible as long as Juve sign another attacking mid. Regardless I think this type of player is needed to compete and rotate with Dybala. Dybala is much better as a support striker rather than a #10.
Costa can also rotate with Sandro as a very attacking wingback. Pep used him like this at times. This makes a 3-4-3 or 3-5-2 with Costa out left a possibility.
Costa, Nzonzi, Schick, and an attacking CM or playmaker would greatly improve the squad. It would give them a lot of tactical flexibility.