For those interested in this topic, John Carmack mentioned NeXT systems a few times in his .plan (see this archive).

The last of the systems was shut down on March 21, 1998:

I’m a bit nostalgic about the NeXT systems – the story in the Id Anthology is absolutely true: I walked through a mile of snow to the bank to pay for our first workstation. For several years, I considered it the best develop- ment environment around. It still has advantages today, but you can’t do any accelerated 3D work on it