They're goal goes far beyond firearms. The destruction of the 2nd Amendment is a necessary step in achieving complete control. They will compile databases, create taxes related to firearms, limit magazine capacity to 10 then 7 and then anything at all.
They may not be able to just go door to door confiscating but they will begin the slow squeaze. They will do it through congress if they can or by executive order if they can't.
Pretty soon all but the most hardcore freedom lovers will have given up on gun ownership. There will be too much red tape, too expensive, and too impractical. How many people will hang onto their AR's if they become illegal to pocess? Most will turn them once they realize that although no one knows they own it they will never be able to shoot it again.
I think this current wave of gun buying across the country is similar to the tea party in 2010. A wave of people with good intentions but ultimately not very effective. I think the clock is ticking for us gun owners.