I personally think used car dealerships are going to eventually go the way of the dodo. It's just a matter of time before sites like craigslist on the internet take over the traditional dealership role. Avoiding the hefty tax that you get when dealing with a used car dealership is easily avoided for most folks, and a simple, cheap and easy warranty can take the place of any other benefit you might once have gotten from dealing with one.
The automotive industry is in for a much ruder awakening that has already come, IMO. And, IMO, good riddance. I despise dealing with car dealers and service centers. For too long they have had too much control over one of our basic necessities in this society - transportation.