Eh, I like the fact your trans can go third job, if just for longer character life...or getting people to play that trans they abandoned so long ago. But that's just me. Although, I do recall hearing about people making 99/50 non-trans characters just incase that didn't happen XD
As for the third jobs themselves, I'm expecting them to sort of renovate the classes....as in swing the classes in a new direction, I guess. Like Knights having some sort of magical ability instead of just being tanks that hit stuff til it dies.