4K vs 8K on a 49" screen across the room is going to have much less of a noticeable difference than 4K vs 1080p on a 24" screen a foot or two away (dancing around the boundary of retina).

I think an 8K 42" would make a great single monitor for productivity, I just can’t imagine driving 8K at idle is very efficient if there aren’t software/firmware solutions to recognize non-moving screens.