But more than that as it appears to be going to support and different style rear fuse like a complete new livery...unless it's a club livery.
They are going to have to change eventually. The A.300 were all grey then AA stripped them and Airbus couldn't guarantee the skin from corrosion as it was pre treated on the line and intended to be painted.
The AA One-Eleven order was a special order as no One-Elevens apart from the AA fleet and two 400 prototypes were built with bare metal on the airframes.
Modern plastic aeroplanes just don't look the same. Leave a 707 or DC 7 unpainted and it's smart. leave a plastic aeroplane unpainted and is a badly made Airfix kit.
This 777 was flown to be painted (it was in standard primer) and it looks like it's just a basic livery awaiting perhaps an unannounced design
I remember one of the G-HDB 748's being rolled out in a mystery livery..grey top blue bottom and blue top to the fin...totally anonymous...The all blue engines in particular were odd and a departure from the contemporary norm.
Nothing was said...and then a 737 and 747 suddenly shot to fame launching the new BA Landor livery/.
Not uncommon to see a few hybrids appear joining a fleet just before a big change.
![Thinking *-)](./images/smilies/eusa_think.gif)