UA got it right from a customer perspective. From a business perspective it's not clear this is a good move. I do not think that NW or CO could remove a row, add a few inches to some Y rows, and then pay for that by selling the E+ section seats to non-elites. Removing a row of seats can be quite costly to an airline, which is why CO at least is loathe to do it. Look at what happened to AA and MRTC turning into LRTC. CO doesn't see this as being good for their business.