Cellular V2X is coming…
I think V2X is very dangerous.
Think about coverage gaps in telecom 4G or 5G.
How this line platooning will work?
Even now in Germany, if your drive from Munchen to Hamburg you will lose coverage more than 100 times.
There are different types of technologies for self-driving cars and fully autonomous, for sure they (car manufacturers) are thinking about the issue that you mention.
Maybe NW assisted will not work in coverage holes, but V2V type features continue to work.
Yes indeed, but have you thought what is the range of a V2V communication?
And even V2V is subject to fading propagation conditions, failures of decoding, etc.
URLLC for example has a link budget constraint of 10 dB compared to regular 5G.
True. But if Teslas are working pretty much successfully, I am sure the rest can do enough to drive through coverage holes and detect collisions, sudden breaks etc.
Problem with V2V is band and frequency at which they will work, in addition to working on normal band for V2N comms.
Tesla does not need V2V.
Neither Waymo that do not use cellular for autonomous driving.
Cellular is seldom use in autonomous driving just to get updates of traffic jams and to reconfigure routes.
I meant they can detect collisions, breaks etc.
So range is enough (in my guess - haven’t studied it)
Tesla uses radars, camera and LIDARs.
Yes, so the technical gap is to pass that info to other vehicle via V2V or Sidelink, which i dont think is too much big technical leap and can be achieved.
Either way I would not trust my life to platooning cars at 500 msec intervals.
Autonomous drive is good, but pushing it further to V2X and V2V is too much for me.
haha. @RFSpecialist, I am sure Elon Musk and others in industry will do all necessary tests before they give this technology to common people. 
*by common people I meant everyone in world including myself.
Me I am happy with autopilot for now. 
The Range of v2v communication is of around 700-1000 mts and the fading conditions are taken care already by the standard in such a way that v2v works seemlessly
The cars would communicate at 100ms which is good enough to have the V2V applications working