I don't think he's going to quit yet: He will leave when his leaving leaves the party in shambles. Because then he wins, from his point of view.
Got to win some primaries first and since the other candidates are such flakes it should be easy. His supporters are not so much Republicans as they are reality TV fans. So even if he leaves the Republican presidential hopes at zero, his fans will see him as more important than the rest of the party. Which means pretty much the end of the party.
