There won't be a 3rd party spinning off from the GOP. The GOP will fade to nothing and another 2nd party will result as a split between the Democrats.
I think you are spot on with that assessment.
It seems that whenever one or another party heads to the fringes the other takes the center ground. I hope the current party in power stays more towards that center with what they do over the next few years, and doesn’t make a true swing to the hard left. The sky hasn’t fallen yet, although it got close in one way on 1/6.
By the way I think if an individual at the insurrection of the 6th. Made it close enough to the Capitol to touch it they should be facing a federal charge.