I am saddened by this, as Powell seemed to be the only one on that staff with reason and a brain. I think he called it quit because he is tired of being mislead and cannot agree to the way Bush is running things.
I doubt it can because Bush initially wanted him gone (rumour has it anyway, that Powell stated his desire to leave a month or more ago to friends at the UN).
I would be happier if he got rid of e.g. Rumsfeld, and also replaced those on his staff who are way too christian conservative and blinded by their narrowmindedness, and found some staff that can see the bigger picture instead.