If you’re going to change leadership I suggest it’s a good idea to let the new leader figure out how to best run things. You don’t see outgoing national leaders being able to appoint the incoming cabinet. That looks like what Ballmer has just done.
I agree that this is strange. It suggests that Ballmer is leaving much sooner than he anticipated even just a couple months ago (which all the comments from Ballmer seem to suggest as well).
What comes next should be fascinating. If Microsoft picks an internal candidate, I imagine the re-org likely stays in place (unless one of the execs passed over to be CEO is mad about that and leaves as a result). If Microsoft goes with an external candidate though, it’s entirely possible they blow everything up and re-org the re-org.
It’s why incoming Presidents pick their own cabinets. Otherwise, there would be a nightmare of politics.