The world will not be changing in patch 4.0.1. We are planning to apply those changes in patch 4.0.3 shortly before Cataclysm launch. (Source)
[...] New race/class combinations and changes to the old world (including quests) should be patch 4.0.3. I know it’s kind of confusing since we typically release one major patch right before the release of the next expansion. In this case, many of the systems changes will be added in 4.0.1, while a lot of content changes will be added in 4.0.3.
The expansion will then provide players with access to the new races, new zones, level 85 cap, flight in Azeroth, Archaeology, etc. (Source)











This is kind of an odd side question: What is the maximum DPS rotation?
I’ve just been thinking about this as I level as Blood and am not in dire need of the healing from Death Striking. I was guessing it’s the same as the old Blood DPS rotation, using Death Runes for Heart Strike rather than Death Strike (and eyeballing it it seemed like 2x Heart Strikes > 1 Death Strike in terms of raw damage). I figured having this knowledge it may be situationally relevant when you aren’t in need of the healing while not actively tanking, although obviously it’s not exactly a big deal what your tank DPS is.