After Romney's speech today, and the reaction to it, we may be seeing the splintering of the GOP. I don't know if that means a third party, but one is becoming two. Romney's speech was an incredible, jaw dropping attack on Trump. Await Trump's reply. Questioned Trump's stability.
Hopefully the more middle ground Rs leave and are joined by the more middle road Ds and we see a third party being born. One can only hope.