There has been a lot of conjecture on display availability, what type the redesigned iMac would possess. We were expecting something better, we have discussed a ProMotion display, OLED display, some kind of LED Full array. Some thought the larger screen didn't need as many LED zones as other displays.Yes, but you are assuming they can get enough 27” displays
The 24" is a 23.50 inch 16:9, 4480 x 2520 pixel 219 PPI, IPS, glossy: yes, 60 Hz. Its a fairly well implanted edge lit design if I had to guess as no one reports specifically on that. Local Dimming tests don't show regions that you have a bleeding or greater illumination when tested.
The 27" which I said could be as big as 29.5" with the previous form factor could be marketed as a 30" without change how much space it takes up really on someone's desk or workbench.
Apple has multiple vendors for acquiring displays. I am not sure we will see this optional nano-texture again given several display types that been floating as possibilities.
IMHO I don't think Apple really has any display shortages to content with, more its been just really improving the design. Best guess is its a larger version of a 24" iMac with chin, edge to edge LCD screen using full array LED back-lighting to be brighter display then 500 nits. Don't be shocked if this larger iMac also uses an external power supply like the 24". It greatly simplifies how you deal with CPU thermals internally like the latest MBP.