It’s a bit of a nitpick, but I’d argue there’s more than one critical mass, and NixOS is already there for the purposes of tinkerers and some early adopters. General Linux people are next, and it’s probably not quite there, which is I think what you’re getting at.
Since it’s the frontrunner as you point out, I have high hopes it will make it.
Why yes, future person, I’ll fix the spelling.
I didn’t get an underline because it was capitalised, apparently.