This is a craziest place i have ever seen. While Hyjal is sweet and quiet (not only because of musing missing), Caverns of Time are nightmare of 3D and hard to believe. You have to see them :)
Caverns of time will open somehow in future. Until then you can read about them at WOWwiki (http://www.wowwiki.com/Caverns_of_Time) or just make a little discovery trip and visit them. Yes, they are accessible. No dying involved, just go over mountain on right side of place where they reside, then do a bit of regular climbing and jumping.