Normal update time for the ACD is Aug/Sep, and Apple already announced that all their displays will have led displays in them and that it's going to happen this year. Also with the iPhone's screen being 160 dpi , I will not be surprised if the next gen ACD will have 160 dpi. On the other hand, those kind of screens are still pretty expensive and aren't produced in high quantity yet. Maybe Apple is waiting for it to drop in price and have a steady flow of supply. Not like the MBP now.