That particular source is sold out but it's not where a computer manufacturer is getting parts.
The availability is real. You can buy a thinkpad with LPCAMM2 right now, and in fact you've been able to buy that laptop for over a year. And you can get it with 64GB modules, which is what you'd need to set up 128GB on a 256 bit memory bus.
Every AMD and Intel APU has had unified memory for many generations, as have mobile devices. It's sad how many people Apple's marketing has misled about something that's been standard in the industry for ages.
