Let me start by saying that I don't think this has a snowball's chance in hell of happening, but I'm curious what people think would happen in this scenario. Suppose that Clinton and Obama keep trading narrow victories in the remaining Democratic primaries, resulting in Obama maintaining his current narrow lead in pledged delegates going into the convention (as predicted). However, Clinton manages to win enough superdelegates to her side to secure the presidential nomination. McCain, seeing an opportunity to take advantage of the Democrats' divided loyalties, asks Obama to be his vice presidential running mate, and Obama accepts. What do you think the results would be? Would having Obama as a running mate be able to draw enough Democrats and Independents to McCain to make up for the conservative vote that neither he nor Obama appeal to?
As for me, I'm not sure what the results would be, but I would rather vote for a McCain/Obama ticket than a Clinton/(someone else) ticket. It's probably about the only scenario under which I would vote for McCain.