False dichotomy, it's not likely that every single regiment of every single branch of the armed forces and police are all going to choose a single side.
Don't be so sure about that, the Federal government (or more specifically, the DHS) has been currying favor with local and state LEO orgs through funding and equipment distribution programs.
The relatively recent militarization of various police forces is evidence of that, and, much like the USG exerted pressure over west European allied countries to ground Bolivia's presidential plane, they will exert similar control over state and local police forces through "greater cooperation" policies.
Certainly a worry, but one bottom line is who do the local police answer to? Who pays them, who can fire them and make them outlaws with all the latter entails?
One thing that's quite unusual about our system is that policing power is smeared across the local, state and Federal levels, with the vast majority of it at the first. This imposes massive constraints on a would be Federal level tyranny.
The relatively recent militarization of various police forces is evidence of that, and, much like the USG exerted pressure over west European allied countries to ground Bolivia's presidential plane, they will exert similar control over state and local police forces through "greater cooperation" policies.