Apple never really has price drops, they just bump up the specs and charge the same price.
Don't know why you put your focus on the price (I agree that it'll keep that point for a longer time)?
I'd guess 'early' 2013. As we are right in the middle of an update cycle, I find the question about the future rMBP quite legitimate and interesting. Maybe this should be another thread, but what do you people expect from the rev. B spec-wise?
I guess that is how they come to be worth north of $700 billion.