I think what is so refreshing about Gates stems at least in part to the fact he has always viewed this as a temporary assignment. He reluctantly came out of a posh job and apparrently wants to go back to it and so has no further political ambitions. As a result, I think he's more inclined to do what he thinks is the right thing to do more than another secretary might be.

So I think his chances of staying on, even if asked, are slim, but I think his temporary stint shows what a competent individual with no political ambitions or axes to grind can do.