I have no issue with this proposal, though they should really ban feeding for any purpose (including fishing) too. If you want to legally fish for a shark, do it without chum. But I'll take 50%. The legality doesn't change anything for people fishing for sharks, so I wouldn't expect that activity to increase beyond its current rate, assuming they continue standard fish/game enforcement.
It's well past time to just make most/all shark species protected within our waters. There's no reason to treat them any different than marine mammals in that respect. If anything they've been depleted more than whales/seals were.