Yes, it is. It's not at all certain that Trump will go third party. Only if that happens, does it become relevant (IMHO). If it does happen, the USA just might see a third party president elected, for the first time in my life, maybe ever. (I still support Cruz).
With respect, I think you and quite a few of the Trumpetts are living in a political fantasy land. The object of the Trumpetts is to tell moderate Republicans (RINOs GOP-E etc) to go to hell. That message is being heard loud and clear. If Trump wins the nomination, a real possibility, I doubt he will win more than a handful of states outside of the old Confederacy come the general election.
We are driving off a political cliff.