"... we don't currently plan to force a character re-customization on everybody when this comes out. The idea is that "oh yeah, this very much feels like my character I've been playing for years" if you want to change that you can use our character recustomization service or you can go to the barbershop and pay some gold to change your hair or whatever it is."
Tom Chilton said this, atm (it might well be changed) you will need to pay if you are unsatisfied with the changes.