The more and more I hear about reports from beta testers, the more I fear what we will see/have come launch. If the expansion was launched today, it would be a hard kick to the face for everyone playing. With raid testing just now starting, they are a long way from release. However, they aren't giving themselves much time.
We haven't heard anything about the pre-expansion event other than some small tidbits regarding changes to the Blasted Lands. They have eluded to a longer period of time than what we saw with Cataclysm and Mists, in terms of how long the pre-expansion activities will last. As with anything, unless they get tested or stressed we will have chaos when it's released.
I was really thinking the release date would coincide with the 10th anniversary, but now it's looking closer to that December "promise". If they break that promise...we will have heads roll. At this point I just hope we get the expansion at 75-80% completion.