I do think there are many people frustrated with the '2 party system', but most don't understand what could be done. It would be a major effort to dislodge the 2 parties from their favored place, and it is in MOST places that they are. Or rather, the 2 party system itself favors 2 existing parties to remain in power, once power is attained. But there are also mechanisms specifically geared to perpetuate the status quo. Gerrymandering is one example.
However, the biggest change that would weaken them would be instant runoff voting. I strongly believe that with IRV, a quarter of congress would be from outside the major parties within 20 years, probably mostly in the House. There are very libertarian areas, very liberal areas and very conservative areas that would elect people from parties that represent those views. I also believe a centrist party could possibly make some headway. I think all this is intuitive, but we couldn't know unless it actually happened. However, we DO know that it is typical in countries that have more representative voting systems that they DO actually have significant numbers of people being elected from more than just their major parties.