This discussion is starting to remind of a pre-view thread for a DAC over at Head-fi. It pretty much came down to the fact that a $200 DAC now can produce sound just as well as a DAC that costs $1200 (level matched of course). Even with all the low less connectors and noise isolation built into the expensive DAC there wasn't really a perceptible difference between the two. If anything the expensive DAC added distortion in a way which appealed to 'audiophiles.'
I think the main point is what humans can precieve is unmeasureable and different for every person. You will have to overshoot that percetible boundry in order to make sure you got everyone.
OT: How many consumers will be able to see the difference between 2560x1600 and 1280x800? Enough to make money out of it? I think the step is definitely over the line of the percetible boundry. The next step in resolution density will most likely go unnoticed to the naked eye so why pursue it. The primary purpose of this technology is to display information and I think marketing can only carry a product so far.
There is always going to be other areas of display technology they will and can constantly improve on such as contrast, black depth and color accuracy. Even those parameters will get to a point beyond human preception.