It will be interesting to see whether the big DSLR manufacturers start using 'Black Silicon' in their cameras. I have a not-quite-top-of-the-range camera from a couple or three years ago that produces excellent results
at ISO 10,000 and even
ISO 20,000 - and that's still not at its maximum sensitivity. Getting (say) a factor-of-ten improvement would be interesting, although there are many other matters at play. For instance, my DSLR has a 35.9 x 23.9mm, 8256 × 5504 sensor, meaning a rather higher pixel density than today's SiOnyx sensors. But still, perhaps it's a portent of the future...
I know there's at least one camera, out for a few years, that claims a maximum sensitivity of something like ISO 4,000,000. Increase that by a factor of ten and you'd have trouble keeping enough light
out of it!