Certainly is, however you have to look at outgoings too. It's entirely possible a retiree on $50k who owns a 3 bed house in SF is better off than someone on $150k who pays $60k a year in rent for the exact same house.
Yeah but I think you need a much higher income than you used to (relatively) to feel reasonably assured of a comfortable retirement. If you believe that a middle class person should feel relatively certain they'll have a comfortable retirement if they work for 30-40 years, then it messes with the definition of what "middle class" really is.