I'd be more apt to ask the question of what ammo would be next. If you read the ban itself prior to de-banning SS109/XM855, it includes copper core ammunition. That could be interpreted to mean that these lead-free (all copper) bullets are illegal as well. If they can claim these "tipped" rounds are illegal, then couldn't they also go for ANY tipped round regardless of material as well as heavy copper tips on rounds like some of the 308?
Why not 204 Ruger, 5.7, 308 Win, 308 NAT), 270 WM, 300 WSM, and many more?
It's Pandora's box.