A third party has never had enough support to really be viable. Nor have we had multiple alternative parties with viable support. Right now it's all or nothing. If you had multiple new options with nuanced positions (even just filling the quadrants of social/fiscal conservative/liberal), then people could have real options. I admit this is unlikely under the current structure. However, it could take shape with structural changes to the voting process. Yes, even with some of its negatives, ranked choice might be one possible road to multiple mainstream parties.