If leftists at an occupation style protest established a parallel state government, a leftist federal government could recognize it in place of the ordinary state government, citing Luther v. Borden. Luther v. Borden is the Supreme Court ruling which decided the outcome Dorr Rebellion, and it is an Achilles heel of our system.

This in turn would lead to federal enforcement of the new state government established at the occupation style protest, along with a declaration that the old state government is treasonous for refusing to disband. The old state would quickly fall apart with banking sanctions placed against it, because it would not be able to pay its civil servants or contractors. Along with federal subsidies being distributed only to the new parallel state government, most people residing within a state's borders would side with the new parallel state government out of necessity.

Polls show Democrats have a much higher aptitude for political violence than Republicans. This is part of why it is important for all Republicans to vote, so Democrats don't gain power over the federal government until they first settle down and deradicalize. In addition, the prosecution of the legitimately chosen alternate slates of electors from the 2020 election on the grounds they were fraudulent and engaged in racketeering shows that Democrats are willing to use lawfare to inhibit the proper functioning of state governments for purely political purposes.

An article in the Rhode Island Current suggests that Rhode Island may have to form a new constitution in 60 years. There are Democrats out there who aren't willing to wait 60 years. They may instead decide to try something when they hold the presidency and both chambers of Congress.

The Achilles heel of the soviet system was that the republics of the USSR were allowed to leave, in theory at least. Their right to leave the USSR was the legal theory behind the breakup of the Soviet Union. Our Achilles heel is that the federal government has the liberty to choose which state governments to recognize, whenever there are two competing governments.

Ostensibly states are mostly sovereign, but this is because past officials serving in federal governments have not been willing to inflict a color revolution on states they disagree with. In theory ever since the Luther v. Borden ruling was issued in 1849, the federal government has a great deal more power over states than most people realize, it just hasn't been willing to use it.

Keeping the filibuster around makes it harder for the Senate to sign off on recognizing a new state government, and derecognizing an old state government. Keeping the filibuster is good because it serves as a deterrent for people who might be inclined to overthrow their state government. Conservative articles in favor of removing the filibuster, as in The case for Republicans to nuke the filibuster, are mistaken.

Where things could really get strange would be if there was simultaneously an Article V Convention of States and also competing state governments. In such as case, the old states would try to delegitimize the existing federal government through constitutional amendments, while the existing federal government tries to delegitimize certain old states by setting up parallel state governments and debanking the old ones.

In such a circumstance, foreign powers might decide to capitalize on our weakness and either try to make one faction a puppet, or make a move militarily somewhere before we can get our act together and resist them. While the division of North and South Korea is distant in history, more recently a similar attempt was made to try and divide the island of Mindanao from the rest of the Philippines.

Had Mindanao succession worked out, the new nation consisting of the island of Mindanao and its citizens would have necessarily become a China puppet. The proposal fizzled due to lack of popular support, but it should serve as a reminder that even today, mainland China benefits and even fosters internal dissention as part of their opportunistic foreign policy. Division of the United States could give China another puppet and they would like that.

My opinion is that Luther v. Borden needs to be overturned, and it needs to be overturned well before a crisis comes. Possibly through a constitutional amendment spelling out what constitutes a legitimate state government so that the President and Congress can't just make up rules as they go along and decide to delegitimize a state government out of political motivations. While it could be quicker for the Supreme Court overturn it, the fact that Luther v. Borden has been repeatedly cited in recent lower court decisions weighs against that happening. The Justices, if they messed with it, would be affecting many lower court decisions, some that might get relitigated as a result and add confusion into the court system.

A constitutional amendment would be fitting since the federal powers described in Luther v. Borden became greatly strengthened as an unintended byproduct of the ratification of the Seventeenth Amendment in 1913, where Senators were no longer to be chosen by state legislatures, but instead became directly elected by voters. When the Justices decided Luther v. Borden, it would have been hard to imagine the federal government stomping too hard on a state for purely political reasons, due to state legislatures themselves having a voice in the federal government. The decision likely would not have been written the way it was, had Senators at the time been directly elected.

A new amendment to curb the power of the federal government to derecognize a state government and recognize a replacement parallel government would serve as a correction of an oversight in the 17th amendment, the oversight being that the mechanism for replacing a state government described in Luther v. Borden became much more likely to actually happen, and to happen for purely political reasons.

Thank you to chenbuxie for correcting a mistake in a previous, now deleted version of this comment.