Let's talk: Advanced Jobs

[Kallera]

I would say that the base classes (Gladiator) branching off into multiple Advanced Jobs (Similar to Skill Tree) seems most likely.
GLD (PLD/DRK)
MRD (WAR/BST)

The reason I think having the Jobs move into Advance Jobs such as the layout in the OP is that endgame will look like this.

SCH x 2 + THF x 2 + DRK + 4 -> Given the idea that all Sub Jobs skills will be available to Advanced Jobs + New Advance Job Skills

That is unless they take it all the way and have an Advanced Job for each pair of Job classes.
(BLM + BRD = Dancer)
(DRG + WHM = Holy Dragoon)
(PGL + WHM = Oracle)
(GLD + BLM = Geomancer)
etc, etc, etc,
Which would be huge. Possibly too huge.

I think the thing people are looking to do is provide an excuse for someone to level said new job once more. Remember that jobs share the experience of the class that they are based on.