The thing is we haven't seen how much they plan on changing that structure for ARR yet. Keep in mind as well that this game includes weapon skills as learned abilities (so the base class could provide the sword-skills you expect of a blue mage while the job provides the monster spells). In addition to the way that BoB and I had discussed as having a base class that branched into beastmaster and blue mage, it's possible that they could introduce a fencer class and from that you'd get both red mage and blue mage.

Because all the classes are new to the series, it could work in any number of ways that you would see blue mage.