I personally wouldn't be too concerned about digital video constantly jumping up in resolution, you can only bump it just so far where few people, if any, can tell the difference between the new resolution/format and the old one. I think that we're more likely to see an eventual shift in medium over ever increasing resolution be it glassless 3D, holograms, VR movies plugged into your brain, who knows but I am certain that the resolution increase will eventually stop.
You would think, yeah. I mean, at a certain point, it becomes prohibitively expensive or impractical to have a screen big enough that you can see the difference in resolution. Like, ok, you've got a 4K Purple-Ray player with a 12.2 DTS-Mega-HD sound system...but the screen is 60" so are you really even able to see the 4K resolution in sufficient detail? Ultimately, I think it's those kinds of size considerations -- given current technology, anyway -- that limit the resolution issue.
But at the same time, I can't help but wonder if film still offers more flexibility down the road, if the value of a property is based not merely on its theatrical run, but on its long-term saleability. Like, with the prequels, how good is upscaling gonna look to higher-res? Or how will they adapt this stuff to holographic displays or whatever?
Actually, what I see happening is the TV-panel industry slowing down some in terms of the perpetual growth in screen size and such, and shifting to more energy-efficient, thinner, lighter-weight models that focus on picture clarity, processing speed, etc. As plasmas fall out of production, the burden will fall to LCDs and OLEDs to improve how they handle things like rapid motion and such. I find motion interpolation to just look AWFUL. I go watch movies at friends' houses who leave motion interpolation on all the time and it drives me insane how artificial it looks. I turn it off and they say it looks weird and choppy (I guess because now they're brainwashed...) whereas, to me, it just looks like everything's been shot on videotape.
If you can't focus on increasing resolution, you can focus on improving the rest of the viewing experience, integrating with other electronics, offering better ancillary services (my Panasonic TV's wifi is worthless, and it's got wonky wired internet, too), and so on. I'd figure that's how the industry keeps people interested. The other big area I see changing -- which might lend itself towards stabilizing resolutions -- is streaming. As streaming services become more widely used, bandwidth will be a limiting factor as the country's infrastructure can't support (currently, anyway), people streaming 4K images or whathaveyou. So, if 1080p is the industry standard for streaming, and most people use streaming instead of other home media, and if the entertainment industry wants more centralized control over it...then why worry about constantly increasing resolution?