The lack of an exit plan was deliberate. This was brought up as an issue long BEFORE the Civil War. Should a state be able to secede, then it would be able to use the threat of secession as a means of political coercion; In turn, the state for whom secession would be most plausible would become more politically powerful, and the entire union would pretty much become a joke.
How would a state even secede, without annexing federal property? Not an idle question: this was the problem that so quickly led to the South attacking Northern troops. The North had pulled back its forces from most federal forts in Confederate territory, but it was hardly clear that there was any intent to vacate Ft. Sumter, rather than staking a claim. Should the Union simply have given the confederacy what was created by the states as a union? Would a farmer who held land in both Maryland and Virginia be expected to forfeit his land in one of those states? So long as both parties didn’t desire the split, it seems unimagiable that a fair outcome could result.
HOWEVER, there seems no reason that should CONGRESS want to CREATE an exit plan, it couldn’t. While there would be an unimaginable number of political and legal issues to address, legislation could certainly allow for a legutimate means to address them.
[ The lack of an exit plan was deliberate. This was brought up as an issue long BEFORE the Civil War. Should a state be able to secede, then it would be able to use the threat of secession as a means of political coercion; In turn, the state for whom secession would be most plausible would become more politically powerful, and the entire union would pretty much become a joke. ]
I would say the conditions or a state leaving should at least require 1/3 of the OTHER states agree that it is okay in their state legislatures for that state to leave, plus the super majority in the state itself. As well as a very large super majority of the citizens and state legislature vote to leave. That way any thought of an individual state using as blackmail can be vetoed easily by the rest by 2/3 majority veto of other states.
That would be a check on the possibility of “state secession blackmail”