Interesting discussion, yes. There was a similar article around industry 4.0 and "the return to the unique lotsize 1 product" in a German weekly paper, and the prerequisites of information technology on the shop floor.
Will we move to a lot size of one in mill? Will we see mass customization in our industry?
First of all, which is "our" industry. I would say that I do not expect any customization (except maybe with regard to colours) in cement, concrete, pulp and paper and similar industries.
If you move closer to the end-consumer in the value chain, this may be different. Building products like doors, windows, frames, even tiles, and even sanitary ware are obvious products where people would like their own style and features with it. To a certain degree those are already MTO today - at least if you order a large enough quantity.
I have not seen this level of make-for-me personally in our industry, but would expect rather sooner than later. Order tiles with an uploaded & self-created design, or carpet and curtains with your own "tartan" - why not.
An important question will be the effect of lot size on cost per piece, or the impact of set-up time. We have to find ways to manufacture where it does not make any difference whether the next item has the same or a different spec. Thinking only of color application, this may require some smart engineers. Currently you have to go from light to dark colors and do a thorough cleaning of your equipment before you can return to light colors again. The faster you cycle, the more you clean - at least with todays equipment.
Regards,
Stefan
PS. Well, after a bit of research I have to say, the sky is not even the limit: NASA's 3D printer makes pizzas for astronauts | NDTV.com