From the 5.2 patch notes:
The Isle of the Thunder King is the new daily questing zone, with the Kirin-Tor Offensive led by Jaina Proudmoore and the Sunreaver Onslaught led by Lor'themar Theron. Doing quests will unlock the powerful Lightning Forge, which will allow Blacksmiths to forge mighty raid-worthy items, as well as classic weapons from the past. Other features will also be unlocked by your realm's participation in the war effort.
First thing that popped in my head was a return of Benediction in some form (as well as other classic but now gone items).