I feel like he'll quit once he realises he's not going to win, but there are lots of other reasons why he could drop out
@Jesse there is also the possibility he gets removed as he would be too far behind. Elon Musk would make an appealing replacement.
He doesn't seem to have realized he didn't win the last one, yet... what makes you think he'll accept a loss this time?
Seems like accepting anything about reality that gestures in the general direction of him being less than the winningest human in existence is quite hard for him. To my knowledge, he has never acknowledged having a flaw or shortcoming of any kind, and he seems to react very strongly whenever anyone does anything that suggests such a possibility. And that's the face he shows the public, I can't imagine what a wreck he must be in private.