IMAX commercial theaters?
They already have 8K commercial theaters.
To me, it doesn't really matter. I wouldn't mind if my future Native-8K JVC projector has to convert 4K BD to 8K (due to lack of 8K contents). I still get to brag about my 8K Home Theater.
Reminds me of a bit told from a comic I was watching.
Mom: you need to go to college
Him: Why? I already have a job
Mom: So you can say that you went to college
Him: I can say that now. Just because it isn't true doesn't mean I can't say it
Not suggesting you tell people about your "8k theater", but you could...if you wanted to...
In all seriousness, I think it's part marketing like 3D (as someone stated) and part natural evolution of HD. Just like 4K, we need content. If we don't have content, then it's pointless. "Upscaling" to 8K probably wouldn't do much of anything.
Once there is content, then us projector people could benefit if we have a large enough screen, but other than that I think it's pointless.
Now, as
@shadyJ stated, the PC world can benefit, especially VR, but I view VR as a fad as well. Just like 3D, not that many people want to ware something on their face just to play a game/watch a movie. I sure don't.