Nobody is making a 50 seater, you are correct! 50 seaters are being parked, you are also correct but it's far from being dead. How can the airlines afford to park almost 1,000 airplanes over night. These airplanes are still making money, they are not making as much as they used to at some point but apparently there isn't a better option considering SCOPE as well as other things!

Airways 133
Delta 242
American 216
United 342