Originally Posted by
SFO777
Both of those already exist.
There is no pre-security connection between T4 and T5, unless you are thinking of the sidewalk.
The new pre-security connection would be a common ticketing lobby and baggage claim. The new lobby would span the distance between T4 and T5 and take out both the Flagship Check-in and the former Delta One facility.
The new post-security connection envisioned here would join T4 and T5
immediately post-security.