It seems likely, although not certain, that Trump will lose the election. If so, what happens to the Republican party? I can see four possible alternatives:
1. Trump remains in control, the party remains as the populist coalition he created.
2. Trump gives up control, deliberately or otherwise, but the party remains as his coalition, under new leadership.
3. The party reverts to more or less what it was before Trump. Most of the blue collar voters he attracted return to the Democratic party, many of the traditional Republicans who he lost come back.
4. The party reforms itself as a different coalition. Having lost many of the voters attracted by Trump, it needs to find support somewhere else. The obvious source is the center, Democrats unhappy with the extreme progressive policies that Biden at least says he will follow and that the young Turks of the Democratic Party, led by AOC, will push, liberals repelled by the very unliberal approach of the Woke faction.
This is the most interesting possibility, especially for libertarians, since we might find ourselves included in such a coalition.
P.S. (November 4th A.M.) It is now clear that if Trump loses, as he probably but not certainly will, it will be in a very close election. Also that he has been surprisingly successful in shifting minority voters, especially Latinos but apparently blacks as well, towards the Republican party.
I conclude that either option 1 or 2 will almost certainly hold for the next four years.