Resurrecting an old thread to see if anyone who flies this route often (UA 946, LAX-IAD), experiences downguages to the 772 on a regular basis?

I'm flying this route on Friday, and am getting a bad feeling that a downguage is going to happen. My observations so far:

1. When I initially booked, I was unable to select seats in Y, as the seatmap showed Y completely full, yet .bomb showed Y=9.
2. Eventually a few E+ seats opened up on the map and I was able to select a seat.
3. At the 1K 100 hour window, my UDU failed to clear, and still hasn't cleared at about 50 hours, despite C=9 and a seatmap that shows 32 open seats in C. During this same period, there have been NO changes to the C cabin, with only 17 seats occupied. This suggests that no one is being upgraded.

My conclusion is that they are limiting UDUs in anticipation of a smaller 772 F cabin, while protecting a few rev seats until the last minute. The reason Y=9, despite the Y seatmap showing nearly full, is that they are planning on having a LOT of empty Y seats after the downguage to the 2 class 772.

Does this sound plausible? Has anyone observed this type of behavior before preceding a downguage? Stinks if it's true, as I chose a less convenient routing in order to score a UDU to C!