Can't be a nationwide nontoxic mandate, Ted. USF&WS has already mandated nontox for waterfowl. They could expand it to include other migratory species like doves, woodcock, snipe and rail. But they can't do anything about upland birds, nor mammals, nor target shooting. And Congress has taken away the EPA's authority to regulate lead in ammo. So while it could be expanded to some degree nationwide, a ban at the federal level isn't possible. At least not under current rules.
The danger is at the state level, as in California. Other states will certainly try to add more nontox requirements, but a lot of states have many times more hunters and shooters (by percentage of their respective populations) than does CA.