I’m gonna ignore the obvious venom above and reiterate my original point, which is so very on topic here:
The importance of the Democrat 2020 nominee is seriously enhanced by the very real possibility RINOs will join Democrats in tag-teaming Trump and Pence. If that happens, there is no conceivable way Trump et.al. will win reelection. Even without a third candidate, Trump’s prospects are dubious at best.
Historical supporting precedent
Republican elites do not like it one bit when a person with conservative leanings manages to become their party’s nominee. They prefer a Democrat POTUS to a conservative POTUS from their own party.
Consider the election of 1980. The great Ronald Reagan defeated George H. W. Bush in the Republican primary. Even though Reagan selected Bush as his running mate that year, the Republican elites were not mollified. There emerged the “independent” candidacy of Republican Congressman John Anderson, a representative from Illinois. This was back when you could find a Republican in Illinois without a magnifying glass.
Anyway, Anderson won a bit less than 7% of the 1980 vote, a significant number of Republican votes which otherwise would have been garnered mostly by Ronald Reagan. Reagan won, of course, despite the Anderson-Carter tag team. But consider:
Trump in 2016 was able to eke out a victory by only a very slim margin over perhaps the poorest POTUS candidate since Warren G. Harding in 1920. The Democrat standard bearer in 2020 will surely be a far stronger candidate than was Mrs. Clinton. This is a certainty by definition; it makes no difference whom the Democrats nominate.
So Trump will already have his hands full without a third candidate draining away votes, each and every one of which he needs so desperately. If Romney, Flake, Kasich, and other RINOs field a candidate, the 2020 Democrat candidate is a certain winner over Trump. That, of course, is precisely the outcome the RINOs seek.