I listened to the presentations as well. There was some mention of the T-CORE project having made passive provision for where international passengers, whose final destination is in Portland, could enter the landside part of the terminal.
If I heard right, it's at the mezzanine near where the Art Gallery (by Loyal Legion is). But in looking at plans of the airport, and from what I remember of that area, I can't quite picture how that works. And if the long term plan is for the Federal Inspections Services (FIS) to remain in the lower area of Concourse D, that would require a lot of travel up and down escalators/elevators to get from the plane, through immigration and out to an international arrivals area.
The other problem with the FIS remaining down there is that even if they expand in either direction, they're still in a space that feels like a basement, with low ceilings and limited natural light. Vancouver has a
nice immigration hall [visible about 6 minutes in] that's below the departure level , but they're able to create those spaces open to above because the entire floorplate is a
lot wider than the concourses at PDX.