I have some speculative guesses.
They removed it from the promo becuase
1. They want to bumps sales of Z9's for a while and that feauture was a nice way to do it.
2. They realized that Z8's would likely be out of tolerance from the heatbuid up with the camera in this mode active for a very long time waiting for the trigger (perhaps an hour or longer in some cases).
3. Same thing for extending the Pre-Capture reset time from 30 seconds to 300 seconds - (This is how long it will stay active before you need to reset with another shutter half press) - This 300 seconds now has the camera writing to the buffer for minutes on end which generates heat probably similar to video.
I hope I'm wrong and these features will be coming to the Z8. Most of all, I'm hoping they create a Pre-Capture with RAW - Even if that means they have to make it 12 bit HE - (which BTW wouldn't be a bad way to go for regular shooting to get 30 fps instead of 20 fps (if that woudl help them do it, I would gladly take that compromise).
Thoughts?