Regarding the NTSB:
1. It does NOT have any regulatory authority whatsoever;
2. It DOES react to political or objective considerations;
3. Nearly always the NTSB conclusions and recommendations represent rational, albeit risk-averse, conclusions;
I have attended NTSB hearings. I have discussed issues with multiple members. They will react to political, popular or industry pressure to investigate either specific accidents or a class of accidents. Nearly all of my NTSB involvement has been regarding aviation issues.
Years ago, in 2013, they had hearings on lithium-ion batteries in transportation. At the time they had testimony form many and Boeing was on the spot for Li-ion fires in Boeing 787. The only testimony that showed how to control the risks was from a Tesla engineer. Neither Boeing, nor SAFT, their supplier, had a clue. When tiny, insignificant Tesla showed how to do it there was some odd reaction.
Many of their recommendations are not adopted. They have access to solid expertise on many arcane transportation issues. Without any doubt, given their mandate, they investigate matters that significant political or industry interests want to be investigated.
Given their mandate and the popular interest in automated driving, electric vehicles and the like...it is obvious that they were forced to investigate Tesla autopilot.
I'll offer odds 7 to 3 that there will be some recommendations that involve labeling, human driver monitoring and some recommendations regarding emergency vehicle placement, signaling (lighting mostly, perhaps) and some procedural issues, possibly incorporating specific operator training.
Why: they invariably issue Muti-faceted recommendations without any concern about their practicality. They also were responsible for initiating aircraft type ratings, air traffic control procedures, highway signage, promoting a few innovations such as seat belts, airbags and criticized 'swing axles' (e.g.VW, Chevrolet Corvair).
This investigation will be interesting. If there will be public hearings attending them will be educational.
FWIW, I walked out of those hearings in Washington DC and bought TSLA, liquidating 'safe' investment to do that.
So, pay attention to NTSB. For good or ill, it will be educational.