IF Trump doesn't run in 2020, what's the likelihood of a Republican POTUS?

[Donald Trump’s Toupée]

The BIG IF being contingent that Trump completes his first full term (no conviction of impeachment), and he decides on his own accord not to seek re-election.

Should Trump's last two years of his first term proceed how his first two years have gone - controversial but no upheaval scandal - he would leave the GOP still a strong, unified base.

In this scenario, would that lead to a de facto Mike Pence nomination, or would it open the door to a Mitt Romney (please!)? And, further, would it lead to a Republican POTUS?

An additional question to ponder is - What's more likely for a Republican POTUS in 2020: A Donald Trump re-election OR a new Republican nominee?

[I Can Now Die Happy]

If the GOP is united in 2020 under one candidate, then we have a decent chance, especially if the D's nominate Vacuous Kamala or Bernie "even my dandruff is red" Sanders.

If we face a divisive struggle between the Kasick's, the Pences, the Nikki Haleys, the Corey Stewarts, the Rand Pauls, etc...then that would be a real concern.

Beta O'Dork is a scary threat either way though

[pbrower2a]

Most likely the Republican nominee is Mike Pence (in the event of the death, retirement for incapacity, resignation, or (highly unlikely) impeachment of Donald Trump. Pence will get the plutocrat vote, the rancher vote, and the vote of Protestant fundamentalists. But that is about it.

If the President simply chooses not to run, then it is hard to see what charismatic nominee the Republicans can get in 2020. They will need such a nominee.