Cars have about a 12 year half life. The composition of the cars on the road will be subject to that. So even if 100% of the cars being made suddenly were autonomous it would be a long time before most of the cars on the road were autonomous. The insurance industry will have a lot longer to see the changes coming than implied here.
The long life of cars is such that I can't imagine the security mess that will come with owning a 10-20 year old autonomous car. People gripe now about XP not getting security updated, but imagine still having Win95 based vehicles still on the roads that are 10 years past EOL support. People will be irate when their Chevy HAL gets an over the air update that disables the autonomous function after the company lawyers freakout over a hard to patch vulnerability.