I alluded to this earlier today and @LSUMASTERMIND caught on. At this point I don't think it matters, even if he runs 3rd party he won't split anything. Hildebeast goes down.
I think tonight ensured that Trump won't be the Perot of this campaign. Perot declared that he would run as a Republican, but he went rogue before the debates started and was granted an equal seat at the debate table with Clinton and Bush/Dole. I don't even remember if they did these same party candidate debates back then, but if they did, they were very low key. Trump got on the stage tonight and got schooled.....and even if he goes rogue, people are going to remember tonight - and the next one, because he will continue as an 'R' for now; his ego won't let him believe he's done.