Here's the thing. Trumps style and character invigorated people. It was both a feature and a flaw. He was equivalent to a Hockey goon sent in to do much needed damage. Aggressive, relentless, and productive.
But without the style of Trump you simply can't get people out to vote. You can't get people excited for corporate tax breaks and deregulation without a populist appeal to offset the obvious negatives.
And dems are literally the majority of the country and winning the culture war by being decades ahead of the game.
The republican party is done. Witness the death throes. This is literally it.
I think Trump traced a path, though. And by the way, there was a somewhat worldwide turn to populism. Boris Johnson, Bolsonaro, Duterte, Obrador is also a populist even if from the left, Le Pen lost but had a strong showing, and even China put a more populist macho dude in charge with Xi.
The era of the polite politician with a well rehearsed discourse is over, relegated maybe to the role of vice president, see Pence.
Of course, Trump still (it seems) lost, but dude was terrible in everything else. If he was just a little more articulate and more competent he would've won as the results show, it was close. If he hadn't alienated old people in Arizona he would likely be reelected, for example. If he didn't talk stuff such as injecting Lysol he may have earned enough votes to keep Pennsylvania.
My take, for the GOP, is that they should find a Trump 2.0, smarter and younger, and focus on areas with lower levels of education such as Latino voters in Florida with some good ol' Latin American style populism. I think they would have a chance of flipping, in the long run, Arizona, New Mexico and maybe even in the real long term California, while keeping Florida, Texas, Georgia. That strategy would be hopeless in places like Vermont.