I noticed that United seems to have reduced the number of 777s that go between SFO and ORD. And increased usage of A321s. I also noticed that (usually) single 777 flight for the day has the crappy old business 2-4-2 layout vs the nicer Polars 1-2-1 layout. Why did they make these (airplane-type, cabin) decisions for SFO-ORD routes? Pricing hasn't really changed. It still cost up to $1400/$2000+ for a first class seat even on a narrow body plane.

Has the number of passengers flying that route decreased? When they had several 777/787 daily options, those flights seem relatively full. But they've been replaced with narrow-bodies that carry less passengers.