I think they will go with the SCH/SMN road.
that's what those Hymns are for, that you buy with GC seals.
You can specialize in 1 path, but not both/all.
Going all INT for SMN, isn't going to totally gimp your sch though.
So let's say they add another job to LNC, i'd guess it would be a dex based parry tank. Because if they made it str, there would be no trade-off between stats.
And Gridania doesn't have any tank class/job.
Otherwise i'd guess at a dex based ranged class...but there's already archer.
Maybe eventually every class will be able to be any role...