As I have stated here before our Confederation, the first US Constitution, only lasted 6 years because it was to limited in scope for a growing country and lacked a strong central government if it was to live and grow.
I take exception to the thought this country would fail because some might not join or might leave. Our founding fathers did not believe that because in changing to a Constitution they only required 9 of the 13 colonies to agree and then went merrily on its way when 3 did not join from the getgo. In fact RI had to be dragged into joining some 3 years later. Therefore stating that 6 states leaving would be the downfall of the other 27 is a bit much IMVHO as the facts don't support that theory at all.
One only has to remember that our original Confederation demanded that to dissolve or leave the Union required a 100% vote to do so, it was perpetual and stated so! Yet not one person or state threw that fact into the mix as a road block to our new Constitution for it only require a vote of 9 to come into being thus desolving that same Confederation and has not one word about perpetuity.
It is also why my belief is that the Resulting Southern Confederation, modeled after our own, had little or no chance to hold those states together over the long haul. Our own history of that time clearly shows this is what would happen. All you have to do is take in the workings of the 4 years the CSA was alive to see the truth is that the central Government was a mess from the getgo and the State Governors did pretty much what they wanted to do. Georgia's Brown was, in fact, one of the leaders in throwing up road blocks and Stevens, the VP, never once helped in the national government during the 4 years it was in being. South Carolina was another that clearly wanted things its own way. It was bound to fail and war only added to its demise.
I ask you, if you can't stick together when all around you are against you there is no way you can survive over the long haul, is there?