This is something I've noticed with the release of A Realm Reborn and it seemed just coincidental at first but seeing the skills Thaumaturge lost, the Conjurer gained, the rumours that a third class might be required later for jobs, and finally mobs using a few key skills that Red Mage might be coming.
Now hear me out, it may seem like there are other classes that would come first but Red Mage seems like it's a prime candidate to come into play before many others.
Let's start by analyzing the Thaumaturge. In 1.0 Thaumaturge had many more skills but some should stick out like a sore thumb to former Final Fantasy XI players as being key staples of the Red Mage. These include...
Dia
Sacrifice
Poison
Bio
Stygian Spikes
Auto-Refresh
Ressurect
Gravity
Aero
Stone
Bind
Silence
Slow
Paralyze
Blind
What do all these skills have to do with Red Mage you might ask? All of them are in some form staples established in Final Fantasy XI (Dia being their starting skill.)