Your job will give exp to the main class it is considered.
So 2:1 most likely won't happen.
Yoshida did consider GLA getting a job that would Dual Wield, But decided against it.
the question is, was it because GLA doesn't sound like NIN material? or because he didn't want a 1:2 ratio?
Based purely on guesses... I would think;
GLA: PLD or Knight (with 2hand swords comming most likely for GLA, and since the GLA title in japan means something like Sword User... It's the closest thing I could think of. PLD and WAR are already parts of Knight, so IDK. But hopefully the FFTA Armor Break kinda Knights. IDK much about FFTA or FFTA2, since I barely touched them.)
LNC: DRG or DRK (I was originally thinking maybe a SAM with a pole arm, because of the TP generation moves, but with the soul eater effects being a heavy focus, I'm thinking DRK. If not DRK, then SAM here, and DRK to MRD.)
MRD: WAR or uhhh no clue. (Since DRK seems most suited to LNC, I lost my guess on this one.)
ARC: BRD or also no idea. (Some suggest RNG, but I'm taking a guess SE looked at ARC like this "Hmmm this class does great damage, AND stays out of range of mob AoEs? Then it will be just like every other MMO where ranged DDs are preferred, just because of this.... so let's lower their dmg, and find another way to make them useful... SUPPORT!" so yeah... I doubt they would go full DD for a 2nd job.)
PGL: MNK or RDM? (Nothing seems to fit other than maybe THF, with PGLs evasion build, but since yoshida said he wanted to make a scout/NIN class/job after 2.0, that leaves us with PGLs seemingly Melee Mage design... so Red Mage is what comes to mind... but this still doesn't seem like it fits.)(edit: someone mentioned DNC, and I agree, just because I like it, not because there is much to back up the idea :P )
CNJ: WHM or RDM again? (This would remove RDM as a melee mage, but seems a bit more reasonable, all things considered.)
THM: BLM or BLU? (Not much else left, and Time Mage doesn't seem too fitting for any of these. Maybe it is more so for CNJ, since Water and Wind spells were more commonly BLU spells in old FFs.)
So besides Scout/NIN and BST/SMN, we can see there is a lack of good options for a 1:2 ratio.
I would love a 1:2 ratio, but yoshida would probably only have SOME classes have 2 jobs, and then that would be awkward, and in the end, leave us with him choosing 1:1 ratio....
So yeah...
EDIT:
just thought, MAYBE as mentioned above, playing 2 classes together can unlock a 2nd tier of jobs, but the question is, where does the exp go?
(aka GLA CNJ and PGL = RDM?)
This might not sound as crazy as I 1st thought, but who knows...
EDIT 2: Actually, since we have to equip the stone to our "class" to be the "job"
it makes even further sense to just "chose" which class will get the exp.