I think we are jumping the gun on perceived problems.
First off I doubt you'll see a mass rush of people buying 223s for deer or antelope hunting.
I know I wont be giving up my 257 Roberts.
I think the only people you'll see with 223s that would take advantage of this rule change would be ranchers or oil field workers who keep one in their trucks for coyotes 'n such.
A hunter with poor ethics that would blast away with a high cap AR magazine is the same guy that would blast away with any other rifle.
You can't legislate ethics. Those who violate "fair chase" are going to violate fair chase regardless of what rifle they use.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071