The analogy of 1912 and the Bull Moose Party is not necessarily valid, so there is no absolute certainty that history will repeat itself (a one-time vote splitter that reverted to one Republican option thereafter).
Discontent with the Republican Party could be deeper now than it was when Teddy Roosevelt mounted his challenge to them.
The tipping point for a new alternative (for a third party to replace a second party) is about 75 to 80 per cent voter support. Once the alternative reaches that thresh-hold, it would have enough momentum to kill off the remaining support for the defunct “second party” — this has been demonstrated in the politics of other countries where similar things happened in the past.
A certain number of supporters of the original party will hold on for a while more out of concern for vote-splitting than preference for the policies, but when their concerns are rendered invalid by the voting results, they will also jump to the new party. At that point the old party is left with only its inner core of support, likely those who feel entitled to patronage. When the party cannot provide patronage, they too will be gone.
If the Patriot Party does things right, by 2023 the only people voting Republican will be Mitt Romney and his dog.
The thought occurred to me that it might be time to start another new party on the left, try to split their vote in two. The Social Democrats under Bernie Sanders and AOC, vs the Liberal Democrats under Hillary Clinton and some poor chump — the actual 45% that vote Democrat split 25-20, I don’t know who gets the 10% top-up of phoney votes, maybe they split that too.