I saw a comment on Reddit about this 6-7 hours ago suggesting that Carmack had a horse in this race and that we might be best to presume the very slightest of bias in his response(s).

That said, I also view his perspective in this field as tending towards unquestionable. He's always seemed to have had a pretty sparkling reputation as well as the obvious talent.

The tech basically has to be a variant of sparse voxel octrees. Carmack has mentioned it in an interview years ago, It's reasonable to assume he's built his own prototype, as he does with pretty much anything else.

gods have been known to be blindsided by revolutionaries

He, and his company, have done research into the field of SVOs to compliment megatexture.

I don't know enough to say if it's the same approach, but it's certainly the same field, so you'd expect him to know a fair bit about it.

http://www.youtube.com/watch?v=VpEpAFGplnI