"They" meaning about 10 Rino's. If we go 3rd party it will be over forever. Just like Libertarians are not in power and are forced to run as Republicans, Trumpsters have to put up with the Mccain's and Romney's to win the big one. Now that Trump is the Republican leader, you will see him come up with money and support to have about 10-20 not be reelected. Someone like Rubio is licking his chops trying to differentiate himself from Trump thinking Trump is over. Trump will eventually tell Rubio to shut up or join him or he will be primaried. Of course Trump must come up with someone better than Moore of Alabama to get a Trumpster.
Just think about what you are saying and look back through history and find an example of what you are saying ever working. 3rd parties are pretty common and I can't think of one of them working. They are ALWAYS "spoilers".