Of course, we know that is not the end of the story. Their will likely be armed rebellion in the decade following Supreme court decisions removing private firearms from citizens. I do think this would be Americans last straw.
What they'll do is make it a penalty -- if they know you have guns and you don't turn them in, they won't come to your house and provoke a confrontation. They'll just use the IRS or some other mechanism to sweep your accounts. Turn in your guns, or feed your family.
That's why the leftist claim that "nobody is going to come to your house to collect your guns" is irrelevant. There are other ways to force (or at least very strongly encourage) compliance.