Your biggest fears for 4.0

[Kaurie]

That's an ongoing issue for some time, not just Bards, Paladins are left out most of the time unless it's for DF Dungeons.

There's this specific team setup that's the best combo and will leave others classes out, Bard and Paladin are pretty much left out these days, adding three new Jobs will make balance even harder.

While I agree with your base premise, I think you are blowing the problem out of proportion.
For example, on FFLogs, there are more parse clears of Creator Savage with Paladins (9,435) than Dark Knights (6,239), https://www.fflogs.com/statistics/13/#class=Tanks Note that Warriors are at 15k :\
For A9S specifically, PLD = 2.9k, DRK = 1.5k, WAR = 4.1k. So, if anything, Paladin seems more desired.

For DPS on A9S it seems pretty even:
Summoner 2,032
Black Mage 2,594
Monk 2,298
Ninja 2,887
Dragoon 3,362
Machinist 2,104
Bard 2,320