The effect will be, normal capacity mag prices will drop drastically. Outfits that have been holding these to sell when the prices get really really high will dump them. All those used USGI's will sell for about $6-$7, and NIW will be no more than $15 max.
Prices of "pre-bans" will drop, as now they will just be a used rifle, and you can buy a new one just like it for X amount (price of today's post ban).
"Post-bans" will no longer be manufactured, and the ones still on the market will sell to states that have their own AW ban rules. But those rules will now be murky, as they have no federal law to piggyback on, and there will be calls for repeal of those, too.
Prices of used "post-bans" will drop even more than used "pre-bans", because to make it into a real homeland defense rifle, the buyer will have to send it out to have the barrel threaded, etc.
There will be a lot of money spent on replacements for stocks, lots of CAR stocks sold, flash hiders, etc.
And best of all, the antis will stew.
With the formerly marked LEO/Mil/Export mags now being legal for civvies to own, it will be very murkey for any future magazine bans. They will have great difficulty telling old legal mags from new mags. They will have to think up new markings. The whole thing will be a cluster-watchamacallit for ATF and the Democrats.
Every time a post AWB weapon is used in a crime, the newmedia, ATF, and antis will squeel like pigs, SEE!!!??? We TOLD you these are crime guns!
A great time will be had by all!