No, on a long enough time scale most of the junk will precipitate down onto Earth, very few orbits are so stable as to be permanent, but that would cut us off for many years.

Most trips you take in a car are from one location to a second location and then back. Home to work, work to home. Home to store, store to home. You'll have to go backwards in your flying car too.

Adding another dimension to travel doesn't make it better, and when progress fails to make something better, then that is not good progress. If you want an example of this, check out the notion of 'Induced Demand.' If you widen the roads, the traffic gets worse. Widen them more, even worse. What if the road was as wide as the sky? Then the traffic would block out the sun.

What? How does flying mean other people don't exist? Traffic corridors exist in the air. Having this would just induce demand for those corridors and create a demand for more and more infrastructure to accommodate air cars. More corridors that can be flown over, more landing zones, more fuel stations. What makes a corridor good to fly over: fewer people who complain of overhead traffic -> more air highways over poor neighborhoods/unused land. And while you're waiting for your car to get clearance to enter the overhead traffic stream, which seems to take long each month, more and more fuel and time gets spent in your flying car. What you need is the ability to get where you need to go, not necessarily the fastest possible means because traffic will inevitably reduce that speed to a crawl. What you need is a train.

The central problem here is:why does someone need a car, flying or otherwise? Cars are expensive to buy and run and require infrastructure and real estate, they produce noise and pollution, all of which add to the societal cost of cars. So what problem is it that they solve? People need to get to 1-4 locations on a daily basis, some close, some far, most a middle distance. All of the places people need to go are spread over a wide area and probably not accessible to any public transit. What if we solved the problem itself rather than look to a new technology? Especially one which could make all the problems of cars worse?