Food for thought though, is the fact that film is generally shot at 4K and most cinema lenses, and cinema periphery is designed for capture at 4k, projection at 2k (or 4k if IMAX). An overwhelming majority of cinema lenses struggle to not vignette on a 5D and Red Epic, let alone going higher than the Epic's 5k. I feel resolutoin may slow down as if you're RED, are you really going to come out with a 6k camera when no-one can use it because there's no lenses that will actually cover the entire frame size? And if you're Zeiss or Cooke, are you really going to spend all the extra time and money developing lenses for a format that may not take off for another 10+ years, if ever? Do you put your time, money, research, etc developing better lenses for the 98% of the market still shooting <4k, or do you put it into the 2% that might want to shoot 6k+ even though there's no camera to shoot 6k+ at this stage...
I mostly agree with the rest of your post, but you're confusing resolution with sensor size here - there's no reason why you couldn't have, for example, a S35-sized sensor with 8K resolution.