Your idea of an RDM couldn't be implemented, but why on earth would you think they would even want to do that to begin with? Just FYI, SCH is also traditionally a mix of WHM and BLM (as are MANY of the classic FF mage jobs), and SMN traditionally only, you know, summons. You'll note that FFXIV's SMN and SCH absolutely DO NOT follow that model. AT ALL.

I think, unless they are completely crazy, they will made RDM what many (most) people actually want: a magic swordsman. A frontline attacker/caster.

So, really, "the only way" SE could implement RDM is by making a stylized version of it, which is something you should expect for EVERY job in FFXIV. BRD in FFXIV isn't a traditional BRD, either. It's an MMO. Jobs must be robust, not flat like you can do in, say, Final Fantasy Tactics, where jobs only server a very very specific purpose.