On further observation the git repository of the book [0] seems to be quite active. Maybe this book might be finished after all.
But I became disinterested because:
1. Most beginning programmers don't start with C
2. I wouldn't get a chance to go deep and explore the language.
So I shelved it, unfinished.
Flash forward to about a year ago... I had flash of inspiration: change the audience to intermediate programmers.
Now I could skim the general conceptual stuff and get into more details.
One thing, though. C actually added a lot of stuff in the intervening years. I didn't realize the magnitude of the project.
Oh well! Too late to turn back now!
Except literally every indian engineer. They teach C to mechanical and chemical engineers for some reason. (It's not an elective)