If a great pyrenees is shaved, is there a possibility that their coat will not come back?

I have always had my pyrenees groomed. Recently a new groomer at the place of which I will not name, decided he was to matted to be brushed and she shaved him. This was in August of this year. It is now November and all he has for a coat is a bunch of thin fuzz. I was so angry that they did this to him but I am concerned that his coat will not return. Be aware of groomers who do not want to make an effort. She shaved him because she didnt want to take the time to brush him. He is routinely groomed and there was no need to shave him. A good brush out and bath would have done the trick but she admitted she thought it would be faster, then corrected herself with easier to which things only became worse. Now I have a sweetheart of a dog that looks so hideous. He looks as he has the mange or something..I just want to know if it will ever come back. He is 9 years old with sever hip dysplasia. I am concerned that this may be his last year since his coat isnt there to help keep his hips warm from the cold. Any advice would be greatly appreciated.