I think the resolution of the screen and the media you show on it are two separate issues. The screen should be high enough resolution so you can’t see pixels. The content doesn’t need to be as high quality if you have good upscaling build in to your system. I have a lot of old Television at 480p that I doubt will ever get converted and it looks pretty good upscaled to 1080p. Go the next step, and all the 1080p copies of Star Wars will look pretty awesome on a 4k screen. And most probably won’t notice that it isn’t 4k.