My guess is soon after the first company releases this they will show statistics on how much safer their cars are and governments stop sales on new cars that are not level 3 in whatever situations their car handles. (this to repeat again as we move up the levels)

Even if you are right because of the above all manufactures would be stupid to not have a significant investment: the day when they have no choice might be out of their control and if they are not ready they go out of business (or confine their business to poor countries with loser laws - but these countries tend not to sell many high profit new cars).