I am afraid you are right. I had always relied on the Constitution as a barrier against an oppressive government but I am sadly learning that depends on politicains and government officials who agree with me. If they don't, especially concerning guns, what is my recourse? Courts? Not if the same attitude persists there.
Sadly, it looks like we are back to the frontier days. Watch DocRocks video and remember Ruby Ridge, Waco, Elian Gonzalez, and now New Orleans. If the police or other government agency is ordered to take your guns, imprison you, take your property, or whatever, the underlings are going to obey.
In the video the people in the national guard say they can't imagine they're doing what they are doing in the USA, but they do it anyway. A big burly cops slams a little old lady against a wall and onto the floor to take her unloaded gun. A man rants that they cannot make him do what they are telling him to do because of his Constitutional rights. He lost.
As you say, in such circumstances your only chance is superior fire power but the odds are very strong you will die trying to resist the government. Eventually, they have superior fire power.
Honest politicians who respect our Constitution are our only hope. It is very late in the day, the sun is nearly down, but that is our only hope.