The most successful 3d party candidate of all time was Teddy Roosevelt and he only got 88 out of 531 EC votes. No one has got any EC votes at all since George Wallace. Ross Perot got 19% of the popular vote and no EC votes. Whatever his purpose in running, all he did was to take down Bush. Trump might pick up a handful of EC votes in some small, hard red states but in the swing states, they'd all go bright blue as Trump split the conservative vote.
But lets say that Trump did pull enough EC votes to keep either other candidate from getting a majority. That would throw it into the house where Trump would have no party members backing him. Since each state only gets 1 vote in the house, the most likely winner would be the Republican.
