Mists of Pandaria
A true enigma, the Timeless Isle, has drifted in and out of Pandaria's mists for thousands of years. Here, time has no meaning, and the sun neither rises nor sets. Its unique characteristics have brought the Isle under the scrutiny of the bronze dragonflight, pandaren explorers, and the black dragon Wrathion.
(my own words) I find it interesting that something completly new pops up at the end of an expansion, which seems like the beginning of something else. The story has no real conclusion at the moment. Then to have the bronze dragonflight and the black dragon Wrathion, in hope of finding something. It must be bound to something bigger than just a legendary cloak and loot stories.
Also in Mists of Pandaria
Following the Cataclysm and the loss of Nozdormu's Aspect powers, the bronze dragons still can travel between time, but they no longer have control over timelines. Some bronze dragons also retain enough power to send mortals back into the past, as Zidormi demonstrates when she allows players to re-visit Theramore before its untimely devastation.
A time anomaly has been discovered on a mysterious isle off the eastern coast of Pandaria, referred to as the Timeless Isle. The Bronze Dragonflight has sent Kairodormu and the Timewalkers to investigate the nature of the isle's behavior and why it became lost in time - literally disappearing and appearing in different periods of time, while the time itself holds no matter on the isle itself. It is mentioned by Kairoz that the bronze flight's powers have "diminished greatly" and that they can "now only catch furtive glimpses through time".
*Spoiler* Vision of Time chain quest: 'Hidden Threads'
You have kept our mission a secret, and for that I thank you. Knowledge of the timeways, when in the wrong hands, can cause catastrophic devastation. My flight has little power to repair it, now. We must be careful.
(note) There is also a mention of a traitor within the Bronze Dragonflight.
The Future
(my own words) All that I have described above is from Mists of Pandaria, but why does it feel like it's from another expansion about something else than what Mists of Pandaria has been all about! It feels like it has such great potential to be a huge storyline. As I do not believe they would create these stories out of the blue. I think they will be going somewhere with this very soon.
(my conclusion) One of the villains in the next expansion will be the traitor within the Bronze Dragonflight. I believe that the timeways, will be in his\her hands, and cause catastrophic devastation.
This can also be why Blizzard ask about what we like about Stormwind City and which NPC's, as they may create one of many catastropic devastation within Stormwind City.
Don't imagine explosive catastropic devastation like with Deathwing, but more like rifts in the timeways, so where the Park in Stormwind City used to be, would likely be there now if that was a location for catastropic devastation, a rift. Try imagine a frightening lightning round ball around a location, that you could imagine to be a time rift, so within that rift, there is either the past or the future.
Then the Bronze Dragonflight would send their Timewalker to repair damage to the timeways and other such task but it would be far from that easy as the enemy will not be making it easy for you.
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... No?