I think that Dolan is planning on getting rid of Antoni and Walsh this offseason. They're a package deal, if one's gone, the others going to follow closely behind. Why you might ask? Because they were both against pickup up Carmelo... Dolan stepped in and told them it had to be done and I think Donnie just wants out because his decision power was taken from him.
I also think Antoni is just hoping to have his guys play well enough for some other idiotic team to hire him. He's a horrible coach though and we'll be 100 times better without him.