I've been using inexpensive ~40-inch-diagonal 4K (3840×2160) televisions as monitors for quite a few years and will continue to do so. Current one is TCL 43S405 (wife commandeered the Sony 43X800E). A single monitor makes for far less configuration fuss — multiple monitors coerce distinct assignments and as well introduce discontinuities in the midst of the workspace (of which I was once tolerant, but no longer). I have yet to try anything in the 50-inch diagonal range, which would likely work but the periphery might go largely unused.
