Too speculative- there's simply no way to answer your question.
Any new law may or may not look like what has gone before. The 1994 "Crime Bill" AWB prohibited only features- large capacity magazines, flash hiders, etc., and then only on guns produced after a given date (with the magazines, you could stick one in a "post ban" rifle, but the mag was only legal to own if it was made before the law took effect). Some state laws have prohibited actual categories of guns (like CA).
Remember, the President is unable to pass such a law by executive fiat. Congress has to go along with it and right now any such law is DOA on the floor of either house of Congress. Quite honestly, I'd not obsess over whether a law may or may not get passed. Barring a huge shift in public opinion and the makeup of Congress a law won't make it to the President's desk for signing.
