[@NecroKnight]
Soldiers vs militia members usually favor soldiers as even without GPS or whatever, the soldiers are just more disciplined and organized along with usually being better equipped.

Like as Oathkeepers (who have many former war vets in their ranks) I doubt i'd have much success in a direct engagement against a organized military force.  I'd be reliant on ambush engagements and improvised traps on the defensive I suspect.  

Still I don't see how this correlates to the US losing military power unilaterally.  Whatever group restores the federal order is likely to inherit the powerful military complex the US has.