Those kinds of changes and
power level are different. They've said very recently that there will not be a major content patch after power level in this
expansion so I think power level would be safe to say that they know their own production schedule. It just doesn't make any sense to divert work away from
the expansion, which is closer than many people assume, to create another major content patch.
The expansion was far off. With the announcement of
power level there is much more to go along with that announcement which tells me that it won't take
nearly as long to get here. Perhaps I'm wrong and Blizzard is purposely lying to us to throw us off. That just sounds very conspiracy theoryish to me.
However, as Mengsk is not on Korhal during the attack he is able to regroup and renew his movement. Why would it be so farfetched to believe we have
power
level in store. Even if Arthas is killed, which I think Blizzard is going to pull power level on us and try and save his vile soul, there could be hints of
the plague left over and the fall of the Lich King might release these pockets of power level which he has planted throughout the world.