Well written, but going to disagree here.
Neither party is near the point of collapse for none of the reasons you mentioned.
Trump, was never, ever going to win a second term. The only thing that precluded him from winning a second term was turnout. The anti-Trump vote was extremely motivated, the pro-Trump vote was consistently underestimated. The pandemic and the economy were not going to make a difference: Arizona, Wisconsin, Pennsylvania, and Georgia, the four states Biden narrowly flipped, were going to Biden regardless due to a nationwide suburban revolt against Trump at large. Regardless of what happened on November 3, 2020, Biden being elected was going to be the end result.
Activist rhetoric ("defund the police" was a major killer for Democrats in Congressional races), bad polling reports (the polling in the Maine Senate race and the Florida presidential race were abject garbage), overrated candidates (Harrison, McGrath), were all additional factors in how the 2020 election turned out and probably skewed a lot of views, including yours.
The Republican Party's core issue is the metamorphsis of conservatism, which went from an actual governing philosophy rooted in classical liberalism to a sociopolitical tribe that has no real philosophy aside from being a contrarian existence to the "liberal", "leftist", or "progressive" boogeyman of their own creation. Their worldview is rooted in having faith that their position is "the truth", not verifiable fact. Conservatism (or really, anti-liberalism and illiberalism) is essentially a civil religion. There's plenty of polling that provides evidence of such.
The Democratic Party's core issue is underestimating the divide between urban and surburban versus rural. The Democratic Party is a metropolitan party, but often they're not winning in metropolitan areas in an enough of a margin to overcome the overperformance and solid red support of rural areas. Democratic outreach into rural areas has been poor. The neoliberalism that you accused the Democrats of pursuing is essentially the neoconservatism that the Republican Party still believes in, even if its rhetoric tries to say otherwise. The 2017 tax cut, the saber-rattling rhetoric of Trump, bad realpolitik, and the fake populism of the party is basically neoconservatism with a makeover.
Both parties are relatively strong at this point. Why anyone thinks that the GOP (or the Democratic Party) is on the verge of collapse is short-sighted and comical.
