Not to say this would actually change, but absent the TSA, airlines could mostly get along fine collecting zero personal information. It's not really relevant to the service -- all they need to know is that you have a valid ticket. I suppose a name is helpful to have attached to a checked bag, in case of misrouting, but even that could just be done by your ticket/reservation number.

There's no inherent reason your identity is more relevant for a plane ride than it is for taking the bus.