Think people are missing the point. The Iris 5200 Pro will enable OSX to have 650m equivalent power all the time. The main thing people were moaning about is the slight stuttering with the retina resolution. I would love near the speed of the 650m in OSX but with integrated graphics battery life. Epic win.
The rMBP is not a gaming machine and never will be, it is a computer to run businesses on and be creative on the move. Switching between 2 chipsets is messy and not Apple like, but they had no choice in the past.
I want a computer that has great speed in OSX/retina all the time and epic battery life as well. I think that is what Apple has always strived towards and with Haswell/Iris Pro that is what they are going to get. I hate it when I see the 650m kick in when I am using Final Cut Pro as I know my battery life is gonna dive.
It doesn't make sense for Apple to go down the discrete graphics route this time round imo.
I think we will see:
15" with same chassis and screen.
2.4GHz/2.6GHz Haswell with Iris 5200 Pro.
Same memory choices.
Same SSD size choices with improved SSD speed.
Greatly enhanced battery life with claims of the first all work day battery life, 8+ hours.
If we get that I will be over the moon as it will be an awesome OSX based computer.