More like the East-German Stasi than US Customs.

IMO the endgame with ID checking/BDO is for passengers to be required to register/request permission for each flight, including giving a reason for travel deemed legitimate by TSA. (i.e., no mileage runs.) Also to require pax to provide extensive background information and clear a periodic TSA background check to avoid SSSS treatment on each flight. TSA will keep a log of each trip and use data-mining software to associate you with your declared and undeclared travel companions and determine "suspicious" activity and incorrect/misleading permission requests, and such suspicion will be sufficient cause to deny travel.

Once they get pax used to all of this, DHS can drum up some excuse to require checks of your Real-ID and permission-requests to travel interstate on roads. They could also put automated license-plate readers at each state border crossing to augment their travel logs. Once everyone's Real-ID, which they will be mandated to carry at all times, has an RFID chip in it, they can use readers to track movements of individuals instead of vehicles. Those policies may be hard to sell, but if they have people used to the checks at the airport and there's a couple of truck-based terrorist attacks, they can just claim such checks are a natural extension of an already established, accepted, and legal policy.

Then they will effectively have control of all long-distance movement by law-abiding citizens.