Airbus has internally informed that the MSN4 prototype will be painted in the forward fuselage with Qatar Airways livery. It is not the first time with a launch customer logo in a prototype but some people inside Airbus does not agree with that.
In a letter to the local newspaper "La Depeche", an Airbus employee denounces «the stranglehold of the Qatar» and «the power of money» of this airline. And he has sent the Airbus internal & confidential memo –dated on 2/October- to the newspaper.
Airbus has confirmed that this kind of sponsorship is quite standard with launch customers; "30 years ago, in 1982, Airbus painted an A310 with the colors of the two launch customers Lufthansa and Swiss. This is a win-win agreement.”
With the A380 flight tests, the logo of Emirates was painted on the belly fairing of the superjumbo in one prototype. Dubai based airline ordered 90 aircraft of A380.
The MSN4 will be painted early 2014 in Toulouse and will be used "to make the promotion of the new aircraft before its first delivery expected in the second part of next year".
Here is one proposal from JKKW posted in doubledecker forum.
Based on the article “A350 : la peinture qui fait jaser” published in La Depeche