Why? Hibernating to an SSD is pretty fast already.

Imagine zero-draw "hibernation mode" taking a few milliseconds to enter, and "waking up" in a few milliseconds, too. Apply to mobile devices.

Mobile devices have battery, so they can power RAM allowing sleep. Also I've read that Optane is power-hungry, so it won't be used in mobile devices anyway.

This stuff promises sub millesecond hibernation. Things like hibernating between sentences kind of hibernation. Doing that could conceivably extend the effective 'use' time of a laptop with a 99Wh battery to a week or more between charges.

Hmm...still several seconds in my neighborhood.

If it were 0.1 second I think life would be quite a bit more pleasant.

We're talking CPU idle and hibernate being nearly essentially the same. Instant.