Coman is still only 18. He needs a season where he plays regularly. I would loan him out to a team managed by a coach who likes to use players like him.
I am lukewarm on Khedira. Pirlo is most likely to leave in the summer. With Khedira our central mids would be: Pogba, Marchisio, Vidal, "Khedira", Sturaro, Pereyra, and maybe Asamoah. Padoin has shown himself to be more useful in the full back position. Having said all of that Allan is class - to be fair I remember him in only one game - the one against us where he totally bossed Pogba.
A great transfer campaign would be:
IN: Rugani, Allan, Khedira (looks like its happening anyway), Dybala, Berardi, Van Persie, Darmian (although I am not sure that will happen)
OUT: Ogbonna, Pirlo, Pepe, Coman (loan), Matri, Llorente, Romulo
Van Persie's transfer price is not that high (yes he is not young) but fundamentally he is still a class player and several notches above Zaza. Would rather we bring in someone who can make a difference in Europe.
Forwards of: Tevez, Morata, Dybala, Van Persie, Berardi is a good bunch of forwards to have for next season's champions league