I understood all of it and was commenting on the definite 'never' part.
The most important part of Dave's quote is this:
Vibrating air to transfer energy for consumer product charging will never happen on a practical consumer scale at the watt level.
(Edited for clarity; emphasis mine.)
I already qualified this for you in an earlier reply, but I'll say it again and try to be a bit clearer...
Charging a modern smartphone requires 5 to 10 watts, minimum. Sending that much power through the air with ultrasonic, at a distance of more than a few inches, cannot be done safely, reliably and efficiently in a consumer setting. That will be the same at any time. Today or 300 years from now, it doesn't matter.
There may be some niche industrial uses for ultrasonic power transmission. Perhaps to power sensors on rotating machinery, however that requires less than 1W of power and can be confined to a specific area that wouldn't pose a danger to people and animals.
The only way ultrasonic power transfer would ever be viable, on a consumer level, is if the device only required microwatts of power. Maybe 50 years from now when our phones are all running carbon nanotube bio-organic 3D stacked hyper processors that are 800x more powerful than today's SoC, yet only consume 10uW, it might be practical to power them wirelessly with ultrasonic chargers. Then again, you can get that amount of power from an amorphous solar cell, so it might be pointless.
However, today, in the real world where the rest of us live, it's not physically possible. And 50 or even 300 years from now, it still won't be possible to transmit multiple watts of power via an ultrasonic beam. Nothing we can discover about physics will change that.