Originally posted by Winder For people who don't use flash and try to avoid artificial light, ISO 100K is needed. For the longest time I used my 5D (3200 ISO max) with the idea that 3200 was really all I needed. I shot TMAX 3200 for years. With my K-5 I am shooting ISO 4K + quite often with results that are much better than FF film at 3200. Now I find myself wishing for 12K all the time. It is human nature to want to improve. To want to push for better. Let's not stop.
I agree with you to a point, although since APS-C has progressed to a point where ISO6400 is pretty decent, I have a hard time imagining wanting too much more if they can improve even further on that. I'm sure just as you state in your example that I would use more on occasion, but it gets to a certain point where good photos need good light, period. For example, you can't expect your camera to make night time look like golden hour, but you can have the camera let you extend that golden hour just a little bit longer-- that's where high ISO is really useful. Low light wedding or play examples as have been mentioned are also good uses for high ISO, but even these need at least some light to make them reasonable photos. My point is areas and situations where that level of low light performance would be useful to most people for taking good photos is becoming less and less. At some point it becomes a better idea to just bust out the flash.
If APS-C gets to a point where it catches up to where FF is now at 6400-12800 (pretty damn clean), then it will be hard to complain about more. With the K-5 I have already been able to shoot a meeting of Occupy protestors lit only by park lamplight at f/1.8, and that photo was good enough to run with my web story for the event. All that we really need is the ability to shoot scenes like that for larger prints if we wanted.
After that, all I'd want from FF is what I've always wanted-- DOF control, a bump in resolution and dynamic range, and using my FA Limiteds on a full frame camera. Not really anything to do with high ISO. I still think APS-C has some room to grow, though.
As to the original poster's rumor, I was just thinking as I was playing around with my new K-30 that a K-5 matched with the K-30's improvements would be a great camera. Maybe they'll do that along with something else added in to surprise us. Priced reasonably ($1100-$1200?) it could sell somewhat well.