After Nixon abolished the draft, it became academic. Nixon was more concerned with getting the student protestors off the back of his neck and getting out than he was on winning. We could have won it, but not without the political will and the total commitment of the administration that both the Johnson and Nixon presidencies lacked.
If anything good came out of it, it would be the low casualties of the Gulf War in achieving a tactical victory in Kuwait, and a similar approach (thus far) in the war on terrorism.
We still need to learn the not-so-gentle art of closing things out though.