The minute I get a monitor that's big enough, I'll just end up with a camera that generates even more megapixels per frame. I'm at 18 now and if I save up the magic money beans for a full-frame back, that'll jump to at least 21.
I like my 27" (2560x1440) for photo work. I'd like more pixels, but not more screens. I'm not a fan of multimonitor setups and have indeed rescinded my extra monitor at work; I'd rather have the desk space.
A single 4K monitor would be great. 8K would be getting on for perfect. Cash donations to the usual address, please.