My opinion: GC isn't going anywhere. Pardo will have a role, perhaps a major one but GC will be lead designer still. Doesn't really matter. GC isn't some irrational dictator who won't listen to anyone despite what many on the forums seem to want to believe. All evidence points to Blizzard trying to arrive at a general consensus on any major decision before making a move.
Pardo being a part of the equation, is of course, good news. He's talented. GC still being lead designer is also good news. It means Blizzard management isn't a bunch of reactionary idiots.