Give me a 14 or 15.6" screen, 1080p with an 870M or 880M GPU with a backlit keyboard and I will buy. Asus ROG has an 850M on their 15.6, and MSI Dominator has an 860M on their GT60 (15.6") I don't want to have to carry around a 10lb monster just to game on a laptop! hell, Haswell i5 would be more than adequate as TOM's has proven in the desktop space, why not an i5 4xxxU + GTX 880M in a 15.6" format?
There is a newer Asus G551 that will have GTX 860M GDDR5 (and potentially Broadwell). There is a real difficulty stuffing a 870M or higher into a 15.6'' enclosure and keeping it cool, the tech is just not there! MSI tried:
http://www.notebookcheck.net/MSI-GS70-2PEi71611-Notebook-Review.119833.0.html and has FAILED with thermals! It's physically impossible at this point, I reckon, these chips just run way too hot.
Now, why U-series Haswell might not be a good idea for gaming: most of them (i3-4010U, i5-4200U, i7-4500U) have a 15W TDP, it's ridiculous, they die in prolonged workloads in most laptops and they suck at multithread due to lower amount of cores. Apple, and Asus in some Zenbooks, use ULV Haswells with higher TDP (like this one with 28W: http://ark.intel.com/products/75992/Intel-Core-i7-4558U-Processor-4M-Cache-up-to-3_30-GHz), it's a much better compromise, but these chips are RIDICULOUSLY costly compared to normal i5/i7s.
Most modern games will run very well at 1080p with high settings on a GDDR5 860M (and even GDDR5 850M, and even DDR3 850M). I have a DDR3 750M in my Asus N550JV and STILL I can play BF3 multiplayer at 1080p on medium-high (mostly high) settings. So you CAN game on light laptops. Hell, Asus even has a "gaming ultrabook", UX32LN (ULV Haswell of your choice plus GT 840M), though of course it has to drop to 768p on most games to run them smooth at adequate settings. You can game on many laptops with modern nVIDIA cards! (Really don't know about AMD, my knowledge of their stuff is outdated by now.) Especially Maxwell. They solved the issue of low memory bandwidth by adding extra cache to the GPU, even a 850M is a very powerful mobile card.
Wait for Maxwell 870M and 880M if you want top settings in a 15.6'' laptop. Current 870M and 880M are still Kepler and thus run hotter/consume more power. Maxwell is amazing and it's a pity nVIDIA didn't release their top cards based on it right away. I hope they'll appear along with Broadwell!