Whether Tulsi goes the 3rd Party route or not, I fully expect that there will be *at least* one 3rd Party Candidate from somewhere on the Right side of the spectrum. I think that is the only way President Trump can lose. Siphon off the some of the Right with an extremist, or with a moderate Never-Trumper who promises not to use Twitter, and it comes down to the new votes he picks up with #WalkAway, #Blexit, and voters who stayed away from the polls last time. And these same groups could also end up going for someone like Tulsi instead.
I think this will be a presidential election unlike anything ever seen here before (and I think Team Trump does as well, which is why they started fortifying their monetary war chest so early). This may be the final chance for the Leftists to try and stuff the genie back into the bottle and get someone in who will kill DOJ investigations/drop charges. And if the upcoming FISA/Durham (and hopefully Huber) disclosures are rock solid, then a Leftist winds up in the White House in 2020 and tries to make it all go away, that's when this country may slide right into our 2nd revolutionary war.