As much as I would love to have one, the general public will never be ready for it. If the public was ready, there would be many more private aircraft in use. People can barely drive without running into things with lines painted on the road, lights and signs to tell them when and where to stop. Let alone the insistence to use the cell phone, drink coffee, watch movies, read, etc. All things I have seen people do while driving. Can you imagine these same people continuing these habits, while flying?

No. Can you imagine your neighbors, even a tenth of them having these? What happens the first time there is a three car parachute tangle at 400 feet just outside the neighborhood?

Unfortunately for flying cars these are the arguments that keep coming up, and for a country with no will to educate even drivers, a surge in pilots would be a mess.

We'll have flying cars when they can pilot themselves and use a mesh network to track traffic.

Yeah I think there are laws in place that already say you can't fly something like this in populated areas. So unless you're flying in a deserted area you'll be spending the night in jail for endangering lives. :( It's a shame but I don't see this happening any time soon for more then recreational purposes. Unless of course you can get this to pass an airworthness test designed by the FAA. At which point you'd also need to register it as well

This would be a great thing to have, or at least it seems great to have a flying car, yet I am not sure I would like everyone to be in flying cars. I believe this kind of car will not be mass commercialized any time soon, yet I believe there should be a separate license for this kind of vehicle.  
First off, flying cars are too expensive for the average consumer. This is not even including insurance, just the base price of the car.  Secondly, most people would prefer to drive on the road, as this could be deemed as more of an extreme way of traveling, at least to the average automobile consumer.  Watch the video on Paul Moller and his Moller Skycar M400.  This vehicle requires space, it costs a lot, and it makes a lot of noise.   A lot needs to be done before these can be commercialized.  I think more people would buy a Tesla before they would be able to purchase a flying car.  However, I do not doubt some people in the next 20 years will be into flying cars such as the Moller Skycar M400.  I believe that these cars will be used for special needs, like emergencies.
What is needed before flying cars become mainstream:

1. Lower cost entry vehicle
2. Lower sound decibel, as right now it's too large
3. Less space for these flying vehicles
4. Less vehicle emission

So, there are a few challenges.  What would be the impact on our environment with the emissions?  How much do they cost to own and operate?  How safe are these, and would you want people who have ordinary licenses to drive this kind of vehicle?
Note: At Detroit's auto show this year there were no flying cars.  I don't believe this is the way we are headed, and they will be seen more as a luxury and perhaps not even seen in the same league as a "car" as we know it

As much as the thought of a flying car interest me I'm really not sure if that is something that will take place since so many regulations would have to be put into place for safety reasons alone. Even so the future will hold much much more for us in this area I am sure!

"Roads? Where we are going we don't need... roads" - Doc Brown
http://www.youtube.com/watch?v=LKLs9ynZEH0