That would probably require UA to redesign the C/F product, and then spend additional time getting the new config certified. Not worth the extra money and time to switch.
Exactly. I would bet money that UA has also contracted to purchase the 777 interiors, so UA would be scrapping already paid-for materials in order to switch everything over, as well as the costs for new configurations, FAA certification and so on. So all the "OH NOES TEH SKY IS FALLING" about UA ditching F in the
immediate future are misguided, IMO- they'll finish what they started on the 777s, simply because it will take a while for them to evaluate where they want to go with intercontinental F/C. If UA decides to dump F, we'll see it when they start getting 787s and 350s delivered, and when their next cabin refit occurs.