I own a 27" inch iMac and I actually think 27" is pushing too big, believe it or not, I think 21 to 24 inches is a sweet spot, they could offer a 20" and 24" retina display and I would be thrilled. Bigger display isn't always better, unless we are talking a 4 inch iPhone 5 🙂 I am a graphic designer and believe it or not I prefer working on a 21" iMac display in my office vs the monstrous iMac 27" display at my house. For movies and games the larger display is amazing, but I feel the 27" is a little too large to do graphic design work. I also feel that most consumers are trending to mobile devices nowadays, so they are used to working on 4" phones, 10" tablets, 11" to 15" notebooks....so a 20" to 25" desktop would fill that gap quite nicely, then release a true Apple TV ranging from 32" and higher for those movie buffs. 🙂
I for one would go from my current 27" iMac display to a 24 or 25" retina display!
Have you used a new iPad or the new MacBook Pro retina display, it is ridiculously gorgeous!