One things for sure, the next rMBP will be a big improvement & the one to have.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?