The 73 right seat and the way we run the cockpit is probably the busiest seat at United. If upgrade is going to be in the 2-3 yr range it is important to respect how much the fo is doing. At previous airlines I saw people that weren't first officers long enough upgrade and just micromanage and abuse first officers with zero empathy. Not saying it will happen here but right seat time is a great learning tool to figure out the United way to do things.
The unfilled 777 spots are due to the fuzzy timeline on the pratts. I don't think they could get them all back in the timeline that was thrown around with or without the fan cowl issue. Lesser points are the huge question mark of China flying returning, cargo possibility if china doesn't come back, and the fact that the 787 is the moneymaker currently with lines in the 80's. I wouldn't be surprised to see the g line in the 50-60% range until next spring which would be hard on every commuter.