The TPT (Trump Purity Test) will be the first requirement of anyone wanting to join the new party. It wont be a one time thing. Every member will have to retake the test and prove the results every 6 months to stay in the party.
Up until about a month ago, I would have opposed forming a new party. I would have said our battle is in the primaries.
But what happened? We had a majority in the Senate and the SCOTUS, and we were betrayed at every point. President Trump couldn't even have his case heard, even with the amount of evidence he and his team had gathered.
What's worse, it was under the Republicans that the investigation into Russia-Russia-Russia started on much less evidence.
After all of this, if asked I couldn't make the case to stay with the GOP if there was a viable alternative.
If a pro Trump party could be formed that appeals to Trump voters, disgruntled democrats, and people who aren't motivated enough to vote for either party, I just might switch. I'll see how things look in a year.