Looks like 2.5 will be in two installments, some are speculating as early as next week but that does seem soonish on the heels of 2.4 but really, they need to get it done prior to the expansion in March(ish).
1st Part of 2.5's Main Story Arc
Hildebrand finale?
New Dungeons:
* The Keeper of the Lake
* Wanderer's Palace (HM)
* Amdapor Keep (HM)
Video:
[You must be registered and logged in to see this link.]New Raid:
* Crystal Tower (final): World of Darkness
Video:
[You must be registered and logged in to see this link.]2.51
Gold Saucer
* Mini games! Chocobo racing, Triple Triad (yay FF8!) and more!
Video:
[You must be registered and logged in to see this link.]Next Relic quest!
Tons of stuff! 2.5B will have a culminating "Battle for Ishgard" event to lead up to the expansion! It'll be great!