I'm not sure why you are getting the down votes. This has been statistically studied for years. A "first past the post" system almost always lends itself to a two way race.

"A Republican will never win again" is not true. It's true that a Republican espousing the current party's platform will have trouble winning again, but they'll just incorporate new ideas into their platform (sometimes even from the other side) to get into power again. This is the reason Trump made the Reps at least competitive again - people are looking for more nationalist policies (among other things).