You might as well just accept that you're already powerless to stop the US government at this point and hope that the infrastructure we have in place to try to stop some kind of dictatorship from forming will be sufficient. If some Hitler-esque motherfucker does rise up, it's gonna take someone from within the government to stop him. Or a foreign government. Especially since I suspect it'll be a lot of citizens armed with ARs who will actually support whoever that Hitler-esque motherfucker is.