It won't happen in one swipe like this is. They will start by banning high capacity mags, assault rifles, then move to handguns, lastly go at ammo and the legal guns to make them so expensive the average person can not afford them. It will be a gradual deal with justification all along the way like disasters, shootings, ect.
No one will knock on your door and say give me your guns. Even they are not that stupid.
I think you're right about that man. It'll be just how California is doing. All guns must only have a 10 round mag. Assault rifles bought in California have the mag welded to the magwell. I think they will make ammo illegal before the make guns altogether illegal tho or like you said super high priced. Ammo has already gone up a considerable amount in the past 4 years! (hints: obama)