More and more likely: A third-party "real Republican" candidate for president.

[thesquanderer]

91. I didn't remember that Johnson was the libertarian candidate. That could have legs.

He's got a jump on getting on the ballot in many states, and there is an additional base of support to be found there.

Plus there's this:

Monmouth also tested a potential three-way race involving Clinton, Trump, and former GOP governor, now Libertarian, Gary Johnson. In this hypothetical contest, Clinton earns 42% of the vote...Trump gets 34%...Johnson takes 11%.

http://www.monmouth.edu/assets/0/32212254770/32212254991/32212254992/32212254994/32212254995/30064771087/7714a05b-515f-4ad3-bdaa-e72a6e5f8e61.pdf

I read elsewhere that 15% in national polling qualifies you for the debates, and he's not that far off. (Though a well known name like Romney or Ryan would probably get there easily as well.)

What's funny about that poll is that it also says

Johnson is largely an unknown commodity. Just 9% have a favorable opinion of him and 15% an unfavorable opinion, while 3-in-4 (76%) don’t know enough about him to form an opinion.

Getting 11% when 76% haven't heard of you is impressive. An awful lot of people who had heard of him want to vote for him against these opponents (his 11% vote being even more than the 9% who viewed him favorably)... but I wonder if some taking the survey were so unenamored of Clinton and Trump that they would vote for the third choice even if they didn't know who it was!