At this time in four years there's a pretty decent chance he'll be preparing for his second inauguration. Of course he's old and fat so there are no guarantees in life. But most likely think GOP voters will be fine.
This is true, but this election most of them think was stolen. They were thoroughly convinced that Trump was indestructible because he pulled off an upset narrow victory against Clinton in 2016. Many of them are significantly more radicalized now compared to 2008 or even 2012.
The tipping point state in 2020 (0.6%) was closer than the tipping point state in 2016 (0.8%), so if you're going to call that a narrow victory, then call this properly a narrow defeat.
That's wishing thinking. If he runs and wins the nomination four years from now, the same 80+ million voters will come out and vote against him again.
And I'd call a 306-232 victory a landslide, per Trump's standards. Not to mention 7 million more votes. A landslide.