collapse would precede any ethnic conflict, demographic shift and economic depression would lead to the collapse and wouldn't be planned but just kind of occur on it's own with bank failures, entitlements not being paid (ie ss & ebt), police and some military likely to walk if they aren't getting paid but many will stay on and work towards their own ends. they will remain a threat in that regard but constitute many individual forces vying for local control against the wishes of the federal government sometimes still under control of the local state. street gangs would function like militias in urban areas anywhere the formerly prominent force is lacking in its appearance as being dominant, these gangs are often already broken up along racial lines. militias would grow or form where not present sometimes as a necessity out of the forces above being little more than bandits or in failing to appear lesser criminals overwhelming rural and suburban areas. in this way tribalism along ethnic, economic and religious strata would occur not per any plan but just collectivism being the only means of survival and the multi ethnic state falling by the wayside, see the police force in katrina for a real life example. those failing to collectivize will perish, self hating whites will be lined up against the wall if they fail to fall in line with the new power structures. pockets of isolated whites could be fine in such a break up, smaller ones could be surely be overwhelmed but lacking a central power attempting to destroy them, it merely becomes a question of which forces have the greatest amount of arms, resources and organization. even if whites are minority across the continental us they constitute a significant force especially if migration occurs along racial lines. areas like appalachia and deseret are already majority white and would do fine until they fight each other.
United States