According to WarCry's write-up for the event, Brack first dodged the question, but eventually decided it was necessary to address it. He confirmed that a paid character customization service is in WoW's future, but said that the developers haven't decided what it will entail or how much it will cost yet.
Perhaps players will pay to make changes not supported by the barbershop, or perhaps all-new premium customization options will be introduced. If it's the former, then WoW is not headed towards a more microtransaction based future, as that sort of option is similar to the already-existing service that allows players to pay for a name change. If unique premium options are being introduced though, that's a whole different ball game.
[Via Rock, Paper Shotgun]