I don’t know if casinos should disappear. Gambling is more fun when it’s social, and frankly no one should trust a computerized house, and way don’t trust computerized physics for games like craps or roulette. And car dealerships should never be replaced by online, not because they’re so awesome but because you should always test drive a car before buying it.
And I don’t think flea markets will be replaced by anything, flea markets are really an impulse shopping thing, E-Bay is a hard place to wander around in. Online shopping is geared towards you deciding what you want to look for then looking for it, flea markets are geared towards you not knowing what you want and seeing something that looks cool.
Car dealerships are being supplemented by the Internet. My lady just bought a used Acura from a dealer just outside of our area by using Cars.com. She was able to compare a large number of vehicles quickly and efficiently, and find a good deal on a great vehicle. The previous owner left a deposit slip inside the center console compartment, and I was able to find the owner's phone number!