Stormblood will be needed for RDM, just as Heavensward was required for DRK, MCH, and AST. And just like those jobs, I can nearly guarantee that RDM won't have a Zodiac. It may not even have an Anima, and the first "special" weapon available will be whatever the new Anima/Relic is in 4.0. Though they will likely have their "AF" weapon available as the weekly limited Tome weapon.