Most politicians actually want to win, and they actually care at least a little bit about beating the opposing party for ideological reasons, so they wouldn't do a lot of what Trump is doing. But Trump just cares about being the center of attention, so he's perfectly happy burning the Republican party to the ground.
A lot can change in 2-4 years, though. Maybe Trump won't be able to regain enough support, or maybe he'll work out a truce with establishment Republicans. (Hell, maybe he'll be in prison due to eg. the NY investigations, or dead/disabled due to old age.) One thing to keep in mind is that Trump's coalition includes a lot of working-class people who were either picked off from the Democrats or were previously non-voters, and Biden's coalition includes a lot of Republicans/ex-Republicans. If you split the country up into three segments of Democrat-leaning, pro-Trump Republican-leaning, and anti-Trump Republican-leaning, it's very possible that the pro-Trump Republican-leaning segment would be a distant third, though the Democrat-leaning segment would probably have a comfortable plurality among the three.
Another thing that's important to realize is that even if the Republican party is crippled by infighting for 10 years (which is very possible), those ex-Republicans will now be Democrats. This means that they will eventually change the Democratic party to bring it closer to the ideology of the Republican defectors. It's not as if the Democrats have won the game now, and so now they have free reign to roll out eg. AOC's vision of the country. We're seeing the coalitions shift, not the final conclusion of the game where one side wins it all. (It's interesting to compare my thoughts on shifting coalitions from a year ago to what's actually happening.)
Although I've tended to prefer the Republican party in the past, unfortunately the result of the Democrats partially absorbing the Republicans will probably be a worse Democratic party from my perspective, with the Democrats taking the worst aspects of the Republican party. The median between Joe Biden and Mitt Romney is worse than either Obama or Trump IMO.
I agree with a lot of what you said here. I'd say that the neo-cons like Romney hurt by Trump will just become Democrats or still possibly be RINOs as usual. The Dems and the RINO Neo-Cons may as well be called "The party" (like consolidated Communist China) as politics like business seems to be consolidating to a neo-feudal power keg that will continue to divide the once free peoples of the world. The only solution is BTC but they will try to break even that with their "Green New Deal": shutting down energy refinement (Keystone and Colonial pipelines (yeah right Russians attacked this it was the Dems... I bet they honeypoted the Russian hackers to break it like the left always does), raise taxes on coal and other energy sources and shut down infrastructure (Biden's infrastructure plan is a big bilk of FED Stamps for him and his buddies in government) "racist" highways and bridges and I'm not making this up (This came from Buttgag).
https://www.wsj.com/articles/the-agenda-behind-buttigiegs-claim-that-highways-are-racist-11618847867