It only means that device makers will have to agree on a new standard before they can drop the previous one. I agree that it will slow down things, but there is no chicken and egg problem.
And what if they can't agree? Maybe apple make a device so thin that even USB-C won't fit and other manufacturers explicitly decide to hobble them by not supporting a thinner connector.
This law would be great for anti-competitive practices. Lowest common denominator wins by default.
