When all government ...in little as in great things... shall be drawn to Washington as the center of all power; it will render powerless the checks provided of one government on another, and will become as venal and oppressive as the government from which we separated." -- Thomas Jefferson, 1821
The one aspect of secession that troubles me is that the process should really be the reverse, i.e., states loyal to the constitution should continue on as the United States and those unwilling to abide by the constitution should be removed from the union, although ideally only those (urban) portions that have really backed the illegal actions in question. So I envisage a reconstituted United States in which certain urban regions are placed outside the federal union and asked to define themselves as whatever they believe themselves to be, city states, colonies of some overseas power, ungovernable failed states, whatever ... for it is not a matter of states wanting to leave the United States so much as states wanting to reform the United States.
This would need to be “de facto” rather than “de jure” since no court could meaningfully rule on it anyway.