California Senator Scott Wiener is introducing a new set of bills to make streets safer across the state, including one that would change how you drive.
And on the flipside I doubt the system for enforcing it would be particularly safe. GPS locations can be spoofed and some kind of transmitter in the sign can be stolen and moved somewhere else if not replicated outright. All a bad actor would have to do to cause a pileup would be to suddenly turn a 60mph zone into a 20mph zone at an opportune moment.