when will be first foiling lux cruiser yacht in 40-100+ ft range?

mono or multi.

New aero-spacey materials, computer controlled foils and sails so you don't need a dozen highly trained monkeys to make it go fast.

Probably also a foiling MOTORSAILOR able to foil with sails or engine(s)).

Take a foiling dingy, scale up to about 80 ft long to give wide flat hull standing headroom.

Almost certainly need transferable side to side water/fuel ballast.

Interior might need to be little more "open floor plan" and less ornate wood and more "early neo sci-fi" to save weight.

Might have a few safety issues, like a large boat suddenly falling over at high speed, so a few extra sea-going rules would need to be created and followed during foiling. Maybe line the interior with inflated cushions for paddling. But overall maybe a bigger boat is safer.

 

Mostly you've got to worry about pesky superheros coming and wrecking the thing.

 

It is a solved problem. Google "foiling ferry" and you will get hundreds of examples. If instead of a ferry with hundreds of seats you want a yacht-like interior, it is only a matter of decor; the technology is available.

 

I'm thinking of a 20/80% motorSAILOR hydrofoil yacht

Would need a decent bump up in materials and automated sails, and foils.

Since materials, CAD, CAM, controls, etc are getting better and cheaper fast, we'll be able to have cool stuff that today is NASA/Pentagon league only.

 

I followed the build of a 90' Sportfisherman for a couple years that was launched not long ago. Really upscale fancy yacht with probably a million spent before anything material was cut. It featured a horizontal "T" foil on center about midships. Explained as not intended to actually lift the boat up on the foil but to reduce drag and improve fuel efficiency. Fuel efficiency is a very relative term and oxymoron for this boat as it burns as much fuel at 30kts as my 24' cruiser burns in several years at 20kts.