I rather see a 3rd tier of jobs instead of branching out from the 1st tier of jobs.

Lvl 50 WAR + Lvl 30 LNC --> Samurai
Lvl 50 PLD + Lvl 30 THM --> Dark Knight
Lvl 50 BRD + Lvl 30 PUG --> Ranger
Lvl 50 BLM + Lvl 30 ARC --> Red/Blue mage
Lvl 50 MNK + Lvl 30 ARCH --> Thief
Lvl 50 DRG + Lvl 30 ARC --> Beastmaster

and etc. This would put an incentive to you know..actually utilize the multiple jobs.