It won't be long before some of our regular commutes will be labelled "AUTONOMOUS LEVEL 5 CARS ONLY". I expect inner city areas & Motorways first - it could be a decade or more before it completely embraces the suburbs.
Does not make sense , with all the engineers that are Prius drivers and we can't have an aftermarket add on to simulate the safer driving features of the Prius Prime !
I think it would require quite a bit of modification to install all the requisite sensors, hook them into a central computer, and then hook that up to the various applicable systems (steering, acceleration, braking, etc.) and program software to achieve level 2 autonomous features, such as those in the Prime and many other 2017 vehicles, on cars that were not originally built with them. Such an upgrade, even if it was available, would likely cost $2000 or more
It won't happen for 2 reasons at least: 1) other than design flaws which come to light, manufacturers never backwards-design cars. In fact, sometimes they'll go to the extent of designing a newer, but similar item so it won't fit or work on an older mode; and 2) because they want to sell more new cars. Cars have a finite life, the newer models have always (almost) been better than previous and will have newer and better equipment - otherwise, TOYOTA won't have a mid-year model to sell me in 2019/20 - I'd just buy the bits to make my 2016 a 2020 model. Otherwise we'd be driving around in Model T's with Autonomous Cruise, auto wipers but fabric roofs and narrow wooden spoked wheels.
Sadly - quite a few years since I've seen a real Model T - though someone was driving an Austin 7 on the Motorway near me recently. I wondered what the bunched up traffic was as I was approaching my exit - it was doing about 65km/hr in a 100 zone. Fortunately the traffic was light.
Closest I got was driving the boss's brother's Austin 7 Ruby in 1962. Not sure how old it was then, but it had the pedals, conventionally placed clutch and brake with metal button accelerator in the central position. I was restricted to the factory yard and nowhere near the road, but hey! That was better than nothing. Austin 7 Ruby - Google Search: