I can see a few players being unhappy as Hughes signed them and no one likes change. But thinking about it sensibly they are meant to be pros and employued by the club. It really doesnt matter who the manager is its nothing to do with them they are paid to do a job for MCFC.
Most of them have worldcup places to play for - so cant suffer a dip in form (Barry, SWP, Bridge) others were not really playing under hughes and didnt like him it would seem (Toure, Adebayor, Robinho, Petrov) spring to mind)
There will be the nuetrals (NDJ, Kompany, Richards, Ireland, rsc) The ones I can see being the most unhappy are Given, Bellamy and Tevez. They are pros personified, Given has shown immense loyalty to his clubs throughout his career even when they have treated much better national heroes worse (Bobby Robson) I think Tevez will be OK as well as Mancini is a respected coach he will fall into line.
The one we are all worried about is Bellamy, we know what he is like anythign can happen. We hope is is grown up and acts like the proffesional we all know he is and moves on.