The only people I know who like McCain are registered Democrats. I kind of suspect that McCain's advisors are planning to vote for Hillary. And maybe he is too.
Sounds like a bargaining chip for a Democrat Vice-Presidency to me. Quit the senate, allow a liberal senator to be put in his place and he will be the V-P for Hillary.
This may have been his idea all along since pandering to the liberals has been his main agenda.
Let's run a three way race. Duncan Hunter, Hillary Clinton, John McCain. Throw in Nader and Bloomberg. I think the conservative Republican wins since the moderates and liberals split their votes all over the place.