You can put an overclocked Ivy bridge at 4.5 ghz and 32gb of ram and it wouldn't be enough... as the current rMBP is very much GPU limited and VRAM limited.
Unfortunately, even $500 video cards like the desktop GTX 680 with 2gb vRAM (not to mention draws over 200 watts!) barely have enough horsepower to push 30 fps 2560x1600 in Crysis tells you how far we have to go in GPU tech before we'll all be routinely gaming at native retina resolution.
The dock looked good at the apple store. but gaming at full pixels will take a while two or three years. I would love to see apple put out a 40 inch tv with 3840 by 2160 pixels. My problem is My eyes are older and small screens don't do much for me. I have had surgery in both eyes and small tiny images don't work well for me.