Telescope cameras are already way past this. This camera has the advantage of being cheaper and smaller.

Not at all. Even when cooled well below zero and without any Bayer filter I never saw something like this with less than 1/10s of exposure.

I suppose it's a matter of resolution. ARCONS is an IR photon counter with 44x46=2024 pixels. I don't know how that would correspond with a camera's ISO, but you can't get much better than single photons. I'd imagine it's useless to install in your ground telescope, but perhaps in a couple decades, the resolution will be scaled up to compete with current optics imaging methods.

https://arxiv.org/abs/1306.4674

Photon counters were not what I had in mind when you were speaking about astronomy cameras. I remember that around 20 years ago we had 1/100th of magnitude resolution with photon counters compared to 1/10th of the CCDs (SBIG &co.)