I've heard this from a lot of people and I need to ask, how many times are you planning on shooting at night in poor light where high ISO is the one and only thing between you and the shot you want to take? More times than not you're going to have a tripod and you'll be able set ISO to (almost) whatever you want. You're certainly not going to go that high for astrophotography.
The only valid curiosity I can find with this scenario has less to do with ISO and more to do with sensor capability, as in "How much detail can you pull out of a shot that's 5 stops underexposed because of poor light?", and then extrapolate that out for every possible ISO to see just how dark you can get and still freeze motion while preserving color and detail (like
Canon's ISO 6 million camera that literally does see in the dark). It's such a randomly small set of parameters that, while I understand the curiosity, I still don't find it to be ISO specific - unless you're shooting video like the Canon.
For a DX DSLR camera this is pretty darn impressive stuff, and just made a lot more lens and light combinations usable.