It is already stated in the Legacy Campaign notes that you will have an opportunity to put your name in the 2.0 credits:
http://lodestone.finalfantasyxiv.com...gn.html#legacy

3. Legacy members can request that their name be displayed in the credits for version 2.0. One name per service account can be listed in the credits.
They probably won't start taking applications for that until they are in the wrap up stage of 2.0 (probably during the beta)