I would think that maybe they can save a very low proportion of chips with ECC not-working, but the large majority would be completely arbitrary market segmenta

I would think that maybe they can save a very low proportion of chips with ECC not-working, but the large majority would be completely arbitrary market segmentation: handling of ECC is going to be limited to a small relative surface area of the die. Now Intel 10nm still seems to be so bad that maybe it is interesting enough to bin on that, and maybe that's the cause Tiger Lake is even more limited on ECC capabilities than before in the various SKU. Although we already saw a restrictive move on Comet Lake. Instead of continuing to multiply their SKU (I think they had enough even 5 or 10 years ago), Intel should go back to the drawing board and ship interesting microarch on better nodes...