> Surely if it’s much cheaper volumes also go up massively…

No, that's not true. If you're making a black and white screen, and you sell it at the same price as a color screen, nobody will buy it. Volumes won't change if your product isn't better than something equivalently priced.

Surely it's both.

1) Product has to exist - and now it does tick 2) Has to be useful tick 3) Has to have possibility of being make cheaper by mass production no idea 4) Has to be put into mass production depends on 3

So we're currently stuck on 3.

Not sure there's much demand for a colour e-ink tablet - but maybe could be layered with a transparent OLED. I'd cough up an extra £100 for that. Normal tablet - with reading mode. Spend a while looking at static image, OLED turns off, e-ink layer fires up. Scroll down and the OLED takes over.

I am so disappointed that Amazon doesn't invest more in the Kindle. They have deep pockets and a guaranteed market. Currently, I am still holding out for an upgrade of the Oasis, but would be willing to spend quite some money for upgraded Kindles and I think I am not alone (even if they just go to 8" and USB-C/Qi charging, it would be worth it). Of course a 10" Kindle would be nice and a true A4 Kindle just a dream.