The biggest mistake people make, is thinking, if technology X was tested and it failed. that in 50 years with new technology and materials it will still fail.
The problem with making a flying car isn't really the technology. We've known how to make a VTOL aircraft for a long time now. The showstopper is the economics of it.
Yes, it is the technology... new technology is what makes the economics work or not work. Successful new technology has always been about making the economics work. Lighter stronger materials..... lighter more powerful engines and motors, denser energy storage in batteries, along with lighter more powerful and more energy efficient computers necessary for controlling all those systems in a more dynamic vertical take off flight mode. I am not saying the economics will work, or that it could be made affordable for large numbers of people, but it is certainly a lot closer to working than it was ten or twenty years ago.
And even if the economics only work for the wealthy, then that still could mean a better overall transportation system with less pressure on existing infrastructure if we take some people off the roads.
Certainly worth some speculative R&D and it is worth support from NASA and regulatory support from the FAA.