I've been wondering about this too. I imagine since manufacturers wouldn't be allowed to sell certain items, that sales would drop and manufactures would have to lay off employees, and small companies would probably go out of business. Who knows how it would affect the economy the way it is.
Wrong. Nothing would change.
If it is anything like the last ban the current manufacturers will change a few cosmetic pieces and life will go on. Magazines will still be available albeit neutered to 10 rounds but they will still be made.
I was only 13 when the last ban went into effect. I didn't realize that they left it open for the manufacturers to just change a little here and there like it somehow makes it less evil. Hopefully this is the case. But like the others said I could see them be happy to put a few more in the unemployment line.