>I'm asking for those 30m who have voted and then show up at their precinct, county clerk/elections, etc pissed off and wanting to change their votes?
I would believe if you mailed-in your vote for a certain candidate, and that candidate is no longer running, you just lost your vote. There is no way you would be allow to vote again. And, there is no way your vote should be automatically ascribed to a different candidate. As far as I know, there isn't an option for voting for "anyone other than X"