It may happen because the Republican Party implodes and one or two parties develop from the ruins.
If you think government is tied in knots now a 3rd party would make it worse. The TEA party is like a 3rd party within the Republican Party and it has Congress tied in knots. A lot could get done by a majority in the House is Democrats and Republicans could vote a body but the Far Right keeps the bills from being presented for a vote. The Left or the middle can do what the TEA party did by getting out and voting. We get what we vote or don't vote for we may not like the results but it can change if people feel strongly enough to organize and get people to vote.
We have 3rd parties in Congress now Bernie Sanders is an Independent he could join the Republican or Democrat caucus.
Look at the countries in Europe. Italy had an election and the three biggest parties each got around 1/3 of the seats. The newest party decided they would not take part so they could not put together a government.