At some point, a State or States will make a declaration, terminate relations with the national government in DC, evict national government facilities from their sovereign country and get on with independence. Of course, they'll have to settle shared debts and such.
At that point, the only ones who will fire the "first salvo" will be the national government to "preserve the Union." Oh, wait, where have I heard that before.
Sadly, it will be people like yourself who will drum up new theories about "universal law" or odd notions of contracts, or perpetual contracts to support the anti-constitutional actions of your national government. As for me, I want to PEACEFULLY seek independence, not attack the national government.
Wait...please be assured that I'm not going to cry because after all "Gad, what a drama queen" I am! What an excellent, profound and well reasoned response. Geez.
The last time someone attempted to unilaterally break the compact it was the initiators - the southern fire-eaters - who opened fire. I suspect that the same same sort of hotheads and hooligans who will initiate their treason again at some point.