I believe just like the military will do the same will happen with the police. Many will not obey and turn and fight for the people. All of this martial law will not be easy for the government. They will need to hide till they know if it worked or not. The elites may end up running or getting killed.
I see this as there last resort. When the economy is in the beginning of a collapse then they do not have a choice so they are preparing as best as they can. This is why they are trying to ban ammo since they were not able to ban guns.
They know the numbers of more then 300 million guns owned by more then 100 million Americans.