I want SAM as tank too, but I am good with either, and with all the hints given from The Rising 2015 event and they have said in interviews its almost assuredly coming, right up there when they kept referencing DRK during ARR interviews. My idea of a good trio (if they stick with only 3 new)
SAM tank, RDM Melee/Caster hybrid, casts magic but needs to be in melee range do some of the mechanics of the job, and a left field job that hasn't been used in FFXI like say chemist for healer. Thanks to what they did with Archer/BRD they can create a class based on consumables that doesn't actually consume an item in inventory. They can make abilities like Mix! that behave like a healer version of Mudra casting using already existing abilities named after flasks.
They also mentioned Blue Mage in that rising stone event but before that event Yoshida questioned whether such a job could/should exist in this game since its so focused on lvling/job questing to get new stuff and that the concept of learning spells in the field alongside leveling would create too wide a gap in player competency in DF groups (Not like there aren't players who don't do the quests either...) because most or almost all would require you get new stuff separate from simply leveling.
