ANY 3rd party is a realistic alternative at this point.
Will they get elected right now? No. Will they ever get elected? Maybe, but not if no one never votes for them. A 3rd party isn't going to go from 1% of the vote to 50% of the vote, but it could go from 1% to 5% to 20% to 50%. It's also possible they go from 1% to 5% to 20% and the major party representatives start changing their ways in order to win back the 20% that aren't voting for them anymore.
Either way, it's a better solution then voting for "the lesser of two evils" and having them consistently make things worse and worse every year but continue to get 99% of the votes.