And despite his disloyalty I don't think that's what he wants, he wants the Bush/Cuck GOP back. He may mount a doomed primary challenge to Trump and/or run as a Never Trump Cuck independent.
Look at what liberals say about him on twitter, they hate him more than we do. Frankly, I don't see why even the most conservative elements of the rat party would be interested in him as a Presidential candidate, he's a pretty crummy politician with limited appeal. The democrats supported a disgruntled nutty Republican (Greeley) in 1872 and it was a disaster for them. For a less ancient reference, RINOs turned democrats John Lindsay and Lincoln Chaffee's attempts at winning the rat nomination were pathetic, and they were lifelong leftists.
McCain BTW was informed that the convention would have rejected Lieberman, or any other pro-abortion Vice Presidential candidate. In any case, McCain was a constituency of one, a moronic nominee wanting a democrat to be his running mate doesn't compare that democrat running for and winning the party's Presidential nomination.
It was understandable given the civil war that Republicans nominated a War Democrat for the nearly powerless office of Vice President in 1864, but they rued that foolish, short-sighted choice the minute Lincoln was shot. That the elderly, cancer survivor McCain failed to learn that lesson was unconscionable.