True, true and true, Clint. I have two plasmas and a Meridian modified JVC 2K non~3D projector and I personally don't watch 3D (as you stated, it MUST be experienced on a VERY large screen) but I have a very large collection of 3D movies (which all come with a 2D BD~V, as well) which I purrchased quite cheaply....just in case!
As with all 'emerging' technologies, I don't anticipate every Tom, Dick and Harry is anxious to upgrade their current 2K flatscreens in deference to TRUE 4K ones and like, you, I am anxiously anticipating OLED as the next big thing (is it Samsung or LG that are introducing OLED screens into their mobile phones).
As far as NHK's 8K TVs.........Overkill plus, IMHO. For movie theaters it might be plausible on a gigundus screen but for the average Joe........yeah, right?
Bandwidth: that IS the issue with 4K. Not enough in the states and barely capable of satisfying 'current' technologies. And very unlikely to do so in the near future.