I'm old enough to see it happen! In 1992, Ross Perot got more than 5% of the vote, so his party was awarded public funding for the next election cycle. By then, Pat Buchanan split from the Republicans and took the help of the new "Reform" Party, but his extremism (mild by today's standards) squandered the party's base.

The Republican Party itself came into being mif-1800s after two election cycles in which third parties won states. It will take a few cycles, and the likelihood is slim. But if you keep voting for the status quo represented by "lesser of two evils", the chance for change is ZERO.