You know how you hear about these other countries, where the government has at-best nominal presence in certain areas? Or sometimes not even that? Those places probably didn't fight revolutions or civil wars to end up that way. They just had a central state whose legitimacy is not recognized in certain areas, and lacks the ability to project a sustainable authority there. I could see something like that taking shape in multiple areas.
This is my best case scenario - a Federal government that looses effectiveness to the point where no one is afraid to not pay taxes, or drill for oil, or engage in any number of forbidden activities because they are confident that they will either never be prosecuted, or if they are, they can make it go away for a nominal sum, and failing that, a well placed bullet. Authority returns to the State and possibly in some cases the County, and neither do a damn thing to help the feds.
It would be a far cry from a law and order based Republic like that our Founder's envisioned, but we no longer have a population that is smart enough or moral enough to sustain such a framework.
But I suspect that those invested in the Fed will not let it quietly pass away. They will either try to hold it together with a foreign war , or they will go full police state - or more likely - both. Get the fighting age men overseas to be killed and then subdue the remainder staying home. . I will not allow either of my children to fight - not over this Fundamentally transformed 3rd world POS Obamanation ( and no that doesn't change under a President Trump or a President Hillary) - and I don't think I will send them out of the country to avoid the draft either.. If they want to fight me over my kids they can do it right here at home and take the bullets coming to them for trying. If they allow an (armed) invasion here - of ISLAM, UN Peace Keepers, Black Nationalists, or whatever, well, I have plenty of ammo for everyone, and the government is every bit as much of a foe in that conflict as the "invaders" -- Perhaps I will be the only one-- but I doubt it. The Fed will push to the point where they can take the gloves off at home, Race War ! We need Martial Law! Islamic Terrorists everywhere! We need martial law and NAZI check points! To keep you safe! All while doing whatever they can to place you and yours in more danger...
and that will push us into civil war if we want one or not.