All of this is underway already. Obama doesn’t have the military, so I don’t personally see anything happening by force. The armed “wannabes” at DHS and other alphabet agencies are not trained urban fighters, they’re desk jockeys for the most part, and they won’t last long against a pissed off and well armed citizenry.
So, the left will use what the left always uses: Informers and guilt and political correctness to achieve what cannot be done by force. It will take another generation or two, but they mean to make it happen. Some of the nonsense in Common Core is frightening, but they are indoctrinating our children and there doesn’t seem to be a way to stop it. The second amendment, and the Constitution itself are particularly targeted in that curriculum.