I think the "Her Art Here" guidelines are a good place to start, meaning:

- Billboard UA wordmark on the fuselage, probably in "United Blue"
- drop the gold cheatline and deeper gray belly, with possibly a different color belly (Rhapsody Blue? Runway Gray?)
- Different tail treatment, with brand-standard globe art (rather than current appearance)

No doubt the rest of the fuselage will be white, and I don't think we'll see any of the accent colors on aircraft ("Premium Purple", "Atlantic Amethyst", "Pacific Blue") but you never know...