Honestly, when it comes to the whole "end of eras" spiel it's not just the US reaching the end of it's current political paradigm (And not a day too soon) but a general global set of norms that looks about to end over the next two decades anyway.
The demographic structures of the relevant world countries was for a long time in a alignment; (the net producers had alignment with net consumers, with the US holding up free trade to 'Own the Soviets' then deciding not to change anything after they succeeded)
That unwinds over the next two decades. The demographics of most of Asia are going to enter decline (Japan is already in population decline and their economy has been stagnant for two decades, and they've had the best tech to take up the slack, but robots don't buy shit, and pensions are expensive).
Watch South Korea and China grapple with this, Korea might have the tech to counter it (And in theory a unification of the peninsula would provide a poor uneducated potential consumer base to keep the south afloat for some time) but ultimately urbanization and feminism has decreased birth rates and that's going to start effecting the world.
The population of Europe has just entered decline. There are only five countries in Europe with positive demographics, only two are relevant (UK and France). Aging populations are not a be all and end all of course, but they produce turbulent politics and lead to declining prospects. Turbulent politics in Europe generally end poorly for all involved.
Germany and Russia are absolutely fucked imo. To start with Germany, their demographics are FUCKED. Pull up a Germany demographic sheet if you want to see. Perpetual decline, and imagration is not helping (most of those 500k syrians went on gibs and are a net drain). Once retirement kicks in towards the end of the 2020s, the EUs financial system is going to get very strange. And that's assuming France doesn't try butting in to take control of the EU.
Russia is actively in population decline now, (but Russian data is garbage so can't be sure) but what we do see points to growth in non-ethnic Russian areas and massive decline in Russian majority areas, we're looking at Russians being less than 50% in Russia by what, 2050?
Eastern Europe will enter active decline in the decade too, and much of their best and brightest are already fucking off to Germany or Britian. Europe's destiny appears to become a dying museum.
And that's before considering the Americans are moving towards isolationism. Without that external security guarantor, Eastern Europe will like become a three-way battle of SOIs between Germany, Russia and Turkey (Neo ottomans do be back baybay, prepare the roach memes).
I remember recently seeing that Spanish is the language most young Europeans are learning (Granted English, French and German are school languages) but I think that the option of escape to the Americas is not entirely lost on them.
The US already has some of the best demographic structures of the developed world, imagine being by bolstered by imagration of Europe's best and brightest departing the continent as the European system collapses? The democrats might actually support closing the borders to keep whitey out lmao.
*The actual experience of your 2020-30s may very*