I have no idea which one will be BLM or WHM...so I will just level up both >.>

However I noticed something interesting.

In FFXI there is a mob called Vanguard Thaumaturge : http://wiki.ffxiclopedia.org/wiki/Vanguard_Thaumaturge
it's job is a BLM. >.> Maybe it doesn't have anything to do with XIV but I thought it was interesting. In XI SE seems to classify Thaumaturge as a BLM.

Not saying that for sure it will be BLM...I honestly have no idea, just something I noticed.