Most of this has been hinted/comfirmed for 2.5 and pretty much common sense from playing the game and checking the history of the amount of content they been placing in each of the past patch notes.

Trial Fights:

Hilabrant Quest/ Gilgameish Ex
New Primal fight/ Odin Hm/ Odin Ex

Dungeons:
Thousand Maws of Toto-Rak Hm
Cutters Cry Hm
New Dungeon: ??????

Crystal Tower 3/World of Darkness

Enemies:
Cloud of Darkness
Ahiman
Cerberus
Echidna (Rumored)
Twin Dragon (Rumored)

il120 Gear

(Gear maybe themed on Xande & Current bosses of CT3 or Warriors of Darkness from FF3)

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New Feature & improvement Added
May Add: Chocobo Breeding/Airship building/Extra Hunts & Adjustments/New PvP Content

Quests:

Moogle Mail Quests x3
New Main Story Quests x16
Hilabrant Quests x4
Dungeon Access Quests x3
Primal Quests x1
Crystal Tower Quests x2-3
Unlocking new type of content/feature Quest x1

Extra:

Bunch of Vanity/Housing items added:
6-9 new Metalic Dyes
3-5 new minions (Expect some from the cash shop/Monthly Reward)
3-10 new vanity equipment
5-7 new housing items

New Crafts
Fill in missing rings/earrings for GSM
New Vanity Items
New Housing items

New Dungeon Gear

New UI Feature