The TSA has been looking for
Credential Authentication Technology (CAT) and Boarding Pass Scanning Systems (BPSS) for years The Desko Penta scanners they have used for years for scanning paper/boarding passes check the digital signature on the boarding pass barcode (at least for those airlines offering precheck boarding passes are digitally signed regardless of whether or not the person gets Pre) but they aren't networked.
Online CAT against the credential would allow TSA to reconcile the person's name/D.O.B. and other info against Secure Flight. In theory, this would allow them to not only validate a person's identity and the matching reservations, but whether or not the person was selected for Secondary or given Precheck.
From the document I linked to above:
Originally Posted by DHS/TSA
In its efforts to address the security vulnerabilities in the authentication of passenger identity documents and/or boarding passes, TSA will send certain Secure Flight data to generate the boarding pass outside of the airport security area; then through TSA’s Security Technology.Integrated Program (STIP) to CAT/BPSS inside of the airport security area. This process allows the TDC to verify the content of the identity document and/or boarding pass presented by the passenger directly against the content of the Secure Flight database that generates the boarding pass instruction. TSA will transmit passengers’ full name, gender, date of birth, Secure Flight screening status, reservation control number, and flight itinerary from the Secure Flight
database to STIP. STIP will then send the Secure Flight data to the CAT/BPSS devices. The data will be securely transmitted in such a way that only the Secure Flight data for passengers scheduled to fly from a specific airport will be sent to CAT/BPSS devices at that airport. If name mismatches occur, CAT/BPSS will display a list of Secure Flight data on passengers with similar attributes (e.g., the same date of birth, gender, last name, and/or first name) that are scheduled to travel on the same day at their assigned airport in order to compare data and resolve name mismatches. TSA will delete the data from STIP and the CAT/BPSS devices within twenty-four (24) hours of the flight departure time. This process will apply to all locations where TSA will pilot and deploy Secure Flight connectivity
Guess we will see how it works in practice, but the documentation describes would stage the reservation data from Secure Flight to the reader. So verification of the boarding pass itself at the checkpoint would be unnecessary as long as the system works normally. (In case of inability to match name or find record, the boarding pass would probably be required).