Weapons I think will be added...

Guns - Musketeer/Corsair (Similar to XI's Corsair)/Machinist (Magic + Gunnery)
Whips - Flayer/Beastmaster/Blue Mage (Keeping the beast-focused stuff on one job makes sense when you consider how actions carry between classes and jobs)
Rapiers - Fencer/Red Mage/Elementalist (they all use Rapiers in previous FF's)
Dagger (not sure what will happen with the existing daggers) - Rogue/Thief/Dancer (seems right)
Katana - ???/Ninja/Samurai (Japanese based company with no Katana in the current game = unlikely to mix katana with regular swords)

This would leave the other jobs with...

Gladiator - Mystic Knight (Rune Knight)
Warrior - Dark Knight
Pugilist - Originally thought this would be the Thief role, however someone mentioned that going to Rogue. So, with that in mind, and assuming Dancer will follow Thief, I guess this will go to something like Black Belt (weaker defence, higher offence or alternatively faster offence, White Monk (healer-melee DPS option) or Gambler (given the nature of the Pugilist Guild, this kind of makes sense... gil toss?).
Archer - Hunter (Ranger)
Conjurer and Thaumaturge - Geomancer and Green Mage - one for elemental focus, the other for buffs buffs and more buffs.