Domestic upgrade: still pay if only one segment clears?
For a domestic upgrade on a two segment flight, if one segment clears and the other does not, am I still charged the miles + copay, or will my cleared segment revert to coach?
In my case I am on waitlist for EYW-MIA-SFO. EYW (Key West) to MIA is very short and not worth the miles + copay. From poking around on EF, EYW-MIA seems to get more C inventory than MIA-SFO, so I may clear that segment but not the other.
I've seen similar questions asked on this thread, but always with regard to an international upgrade, not domestic. I did not read all the pages, so forgive me if this has been answered before.