Pure speculation here, but the high-end 21.5-inch iMac sports a NVIDIA 650M graphics card (640M in the low-end model, and a 660M in the entry-level 27" iMac). Any thoughts, speculation or guesses on what kind of graphics Apple may employ in their next update to the iMac line? (Late 2013 / Early 2014?)
Of course, no one can say for certain.
Of course, no one can say for certain.