I think there is a lot (if not too much) to process in making reasonable predictions regarding political developments, let alone American ones, over the next few decades. That being said, I think it is also fun to think about this stuff and maybe we can predict more than I give people credit for.
First of all, I have never really followed popular politics, but even less so since Trump left office. I did not even know that the CDC was allowing businesses to permit "vaccinated" people not to wear masks until yesterday. Secondly, I want to say that I find modern technological democracy impossible to trust. I do not care how many time the votes were "counted", and I do not care who "won". Modern representative democracy (not just the American variety) itself seems to me to be one of the most effective psychological technologies ever developed which acts as a relatively controllable pressure-release valve and periodic surrogate activity. I simply have no reason to believe that the results of an election supposedly involving hundreds of millions of people accurately represent the votes or interests of people. There is no way to verify the results of an election except trusting the government--the very thing in question--or to count the votes myself which is (probably?) illegal and approaching physically impossible. There is too much proprietary technology in between the act of voting and the announcement of a "winner" for me to view the process as even possibly neutral.
That aside, I am willing to agree with you that Trump's presidency was an indicator of anti-globalist sentiments (an indicator whose strength is up for debate, probably), and this is so whether or not he was actually elected, or selected by the owners of the democratic technology. Obviously he was not substantially anti-globalist, but did superficially embody that stance enough to supposedly beat out an established career politician.
And I think that you are right that within the next 10 years the American political system will come under unsustainable pressure. The following proceeds on two assumptions: 1) there is no other ecological, economic, and or civilizational collapse
2) that Americans are not entirely impotent or domesticated/distracted by the technological system and will actually get off of their mobility scooters/4x4 trucks/starbucks seats and take action based on their beliefs.
The fallout of the prior election (or prior two elections) demonstrate at least a superficial weakening of trust in the system and increasing polarization. At some point the losing side is going to take meaningful action to establish sovereignty against an unrepresentative system. I think a lot will depend on the character of the candidates running. Biden was a great move by the "left" side of the theater since he was 1) not Trump and 2) a career globalist and, by extension, technocrat. If either or both sides run a candidate further "left" or "right" than Trump or Biden in 2024, I do not see the system making it in its present form past that. If Dems run a moderate again and Trump returns and wins, I do not think there would be a break down in 2024 and this would push collapse to next election. If Trump or a right-moderate loses in 2024, I think the "conservatives" are more liable to flare up and cause substantial though not critical damage to the system, and, again, the collapse is postponed until 2028.
In the case of a political collapse, I do not see how the U.S. could remain a "unified" political entity. By '24 and '28 there will be more talk about secession. If the Texas border stuff keeps up, I could see Texas seceding regardless of election results. Apparently California also likes to talk about secession, and I could see them pursuing that if a Trump or Trump-esque candidate wins in '24. Even if they do not do so before everyone else, the results of the elections will likely see blue or red states seceding from the Union. This will not lead to a clearly delineated civil war since almost all urban areas are blue and almost all rural areas are red. There may be a civil war, but it will be urban-rural in character instead of state-state. This state of affairs means that state borders will disintegrate, cities and industry will be decimated, and the economy will be entirely localized if not barter based. Some states might manage to reestablish their borders, and some states might manage to form new unions, but the collapse of the US will probably lead to a global war/power struggle resulting in either smaller local powers backed by stronger global powers (ex. a Western US based state backed by China and an Eastern one backed by the EU) or a total global economic if not technological collapse. If the former, the old US would not be reestablished because it would be silly for the new world powers to reincarnate an ex-world power; if the later, the technological infrastructure required to govern the continental US will either not exist or be unaffordable for the local competing powers.
In the case of political case, local federal governments might exist to keep other local governments at bay, but I honestly do not see there being relatively stable local government for decades except in the least divided parts of the country (divided in all ways; racially, religiously, politically, etc). People on the ground would become much poorer, open to violence, but also more willing to establish communities and focus on the necessities of life, so I agree with your prediction of "a mostly agricultural, small scale production-community oriented society", except that agriculture is going to be hit very hard 1) because once modern logistics collapse, the monoculture fields dominating the US will either be left to rot and recover naturally or forcefully utilized leading to weak and sickly yield and 2) because the vast majority of Americans have no clue how to grow food, let alone enough to sustain themselves.
These are my optimistic predictions or even hopes. I am not confident that the system will collapse naturally or, even if it did, that the resulting struggle would be severe enough to preclude a new, stronger, more centralized, and more technological system that places even more constraints on the people living in the present day US. I do not think permanent stagnation or regression is possible at this point in time, and, while that is what we are experiencing presently, something will give way. The options are violent collapse followed by permanent disunity, violent collapse followed by a new technocratic dystopian union, or a legal reformation into a technocratic dystopia accompanied by petty struggle. Of these, only the first seems desirable.
Again, not a political scientist or theorist. This just expresses some theories that I have absorbed over the years online coupled with my understanding of technological progress.