And what's the cost of retaking these states by force? Is it just to begin a war--costing millions of lives--simply because these states decided that the U.S. government was no longer functioning properly?
Being in the United States is important for all states, and I don't think that states would secede willy-nilly. However, again, I don't think that a country is justified in forcibly requiring a political subdivision to join (or remain a part of) a confederacy.
Yes, I think your scenario is a bad one for the remaining states, but along with a strong central government comes the burden of attempting to please 50 very different political subdivisions. This is the path we have chosen. We must be prepared to deal with the consequences.
Life in Los Angeles is starkly different than in North Dakota, and different things are important to these two very different groups of people. When the federal government was small and unintrusive, governing these two very different groups of people was less of a challenge, since the states were best equipped to deal with local problems. However, as the federal government begins to regulate more and more traditionally local activities, major problems are created.
If this continues, states are going to be unhappy. There will be groups that want out. Let's recognize that now.
But I find it interesting that you see the Constitution as a tool that can be used against the interests of the states. Merely by leaving the Union, any state can use it to bludgeon the remaining state and there is nothing they can do. All the protections seem to apply to those leaving and not the ones remaining. The seceding states can repudiate any obligation, seize any property, take any action that harms the remaining states, and short of declaring war those states have no recourse whatsoever. I can't think that this is what the founding fathers had in mind.