Well, the ban on assault weapons was all about *producing* them from what I can gather. There were still tons left over that were being slowly sold into the market. From what I read most gun shops don't expect any major increase in orders - since most shops already had a backlog of assault weapons they had been slowly selling off over the last 10 years.
At any rate I don't think the ban on assault weapons really accomplished much. I'm not sure there was ever an 'alarming' amount of assault-weapon backed attacks to institute the ban in the first place.