That's actively happening. 94UL was approved a couple years ago, and some of the smaller airports in the SF Bay Area are already dispensing it.
100UL was the last major barrier (since high performance aircraft need 100 Octane fuel), and that was just approved last year. It should start being dispensed at smaller airports soon. There's a lot of pressure to get this in pumps as quickly as possible before the EPA bans 100LL.
(Probably not fast enough to prevent San Carlos Airport in the bay area from closing - the county officially wants to close it due to leaded fuel, though it's an open secret that's just a convenient excuse so they can free the airport land + airspace up for real estate developers. The airport's already switched over entirely to 94UL pumps.)
