I haven't listened to the interview, but I have to believe the focus is on International->Domestic connections. All that really requires is a way to examine checked bags without passenger access -- and that's already done on an individual bases when bags are delayed. Scaling that up to all passengers probably requires photo matching or similar. Then it would be feasible to have passengers arriving from locations where the security is trusted be have a path directly from the immigration counter to the secure side of the airport. This would be a huge streamline for many many passengers.

Allowing no-visa transit is a lot harder, requiring fundamental architectural changes to airports and creating huge new inconveniences for the majority of non-I-I passengers. You either need to make the departure area for international flights a secure holding area (meaning passengers changing their mind or having a canceled flight can't just exit the gate area without immigration checks, and the same gates can't be used for D and I flights), or you need separate holding pens and pathways to every international departure gate. I don't think there's enough value in this for it to ever happen.