If and when Ravnica gets a new set/block in the 2 Set Paradigm and thus an Art of Ravnica artbook and thus a Plane Shift: Ravnica, what races do you think will be available?

6 like on Zendikar?
Human, Loxodon, Vedalken, Vampire, Goblin, Elf?

Or more?
Human, Loxodon, Giant? Vedalken, Merfolk, Vampire, Ogre, Goblin, Viashino, Elf, Centaur?

I suppose the simpler the better, but no playable Loxodon, Vedalken, or Viashino?

A lot of those races have already been covered, so it might be quick and easy for WOTC to include them. I think the focus will be on the guilds though. Maybe they'll act as a character background, granting proficiencies and whatnot, or as a class modifier. If we go that route, I don't think we'll see too many new classes. The other big potential focus is environs- Ravnica is tied to its geographical backdrop more than most MTG settings.