I guess I should point out that we essentially have a third party. What we need is my mom and dad's Republican party back: a center right party focused on governing with a pragmatic conservative vision, willing to work in the system to get things done. What we have now is a party of bomb throwers more focused on pwning the libs and getting on tv ruled as a cult of personality. The best thing that could happen for the Republican party is to marginalize its extreme.
But the energy to form a third party is unlikely to form from the middle. That is why the past thing that could happen to the current version of the Repo party is for the whole thing to get pantsed for a couple of elction cycles so that the party masters slough off Trumpism and get rid of, or marginalize, the Marjotie Greenes and Gym Jordans,