I can’t see as if I’d need a 5K display. The 4K units are coming way down in price lately.
Really, the main delay has been the lack of 200% scaling support for SketchUp.
(Without scaling everything would be about half the size. Ie, Currently I’m running FHD on a 25" external display and I’m looking at going up to a 28" 4K UHD display. This will shrink what I see now down into a 14" diagonal portion of the 28" 4K UHD screen.)
EDIT: I’ve come to understand the stores / sales are misrepresenting UHD displays as 4K, which is a Film industry standard of 4096 pixels wide. UHD is 3840 pixels wide and twice the 1920 pixels width of a FHD display, and also twice the height so it has 4 times the screen space as FHD. It ought to be termed “4X” not 4K.