First and foremost, Ron W, great article on E-AB fatal accidents in Kitplanes this month. Although it is only 4 pages long, I know the amount of time and effort behind all that research and getting the data into nice, readable charts/graphs. Thank You!!!
Flight paths of autonomous aircraft (UBER goal) will typically not cross with J-3s up through airlines as they will be intercity, roof top to roof top and very low altitude. I'm also not sure that whole aircraft recovery parachutes (BRS is a brand name) is a factor either. The vehicles (proposed to date) are powered lift and will have to proceed through "graceful degradation". Ironically, failure modes of powered lift typically result in a tumbling vehicle … an area where parachutes have limited success.
Although I agree on the liability issue, there is A LOT of money in this field. In addition, there are A LOT of non-US companies, where liability is much less a factor.
On the original topic, I think that there are less and less plans availability. There are more and more assembly kits available. There are many more one-off designs, though, of younger people experimenting on their own (and coming up from the RC world). BTW, I loved the flying car racing forum. It is people like this that will cause the next breakthroughs. We old guys call them crazy, but people that build their own airplanes have been called that since the early 50s. Oh heck, before even Orville and Wilbur.