Magazines over 10 rounds made before the last AWB were grandfathered; new high capacity magazines could be sold only to the military or law enforcement agencies (not individual officers). The latter were marked, so that any new magazine in the hands of an individual was illegal.
The current proposals, as I understand, will totally ban all magazines over ten rounds* and any over that will have to be surrendered; illegal possession will carry a heavy penalty; one source says a mandatory 20 years in federal prison. I hate to think what that would mean to a widow who found one in her late husband's belongings, but the anti's have no concern about such things.
*Federal proposal. I understand the NY governor wants a 7 round magazine limit whether detachable or not and on all guns, making the Garand rifle, SKS, and millions of .22 rifles instantly illegal under the "magazine ban."