Flying cars are certainly a nice gadget, but do we really need or want them? I can only think of two good arguments for flying cars, entering the third dimension if we run out of space on the surface and maybe being able to get rid of our current infrastructure, i.e. no longer having to build and maintain roads and railroad tracks and the accompanying infrastructure.
In metropolitan areas it certainly looks a bit like we are running out of space on the surface but I am actually not sure that we are not just pretty bad at making use of the available space. No longer having to maintain a large piece of infrastructure seems actually the more convincing argument to me.