Two comments:

1). There were 31 on the upgrade list MSP-ATL last Thursday. And the flight was sold out. I think there is room to add more hub-to-hub capacity, quickly.

2). The CRJ 900 has 12 first class seats, so 50% should equal 6 occupied seats. Which it did on my flight MSP-RAP on Wednesday. But on the flight back Thursday (RAP-MSP) the gate agent said "they told me to limit it to 5" -- so the plane went out with only 5 occupants in F. Which is ridiculous.