In this respect rating the "expressive power of C versus LISP" depends
very much on the problem domain under discussion.

Of course. I pointed out in my first post on the thread that "[...] for a person of my (low) caliber, LISP is neither suited to the family of problems I encounter nor suited to the machines I solve them on." I cannot exclude other machines and other problems but can talk from what little I have personally experienced.

I would like to see Haskell fill C's niche [...]

Is it as readily comprehensible to newcomers as C? Are there texts out there that can welcome a real beginner in programming and help him become productive, on a personal level at least, as rapidly as good C textbooks--you know the classic example--do? Is there a coherent mental model of small computers--not necessarily what you or I deem to be a small computer--that Haskell fits well and can be taught to learners? I imagine those will be indispensable for any language to replace existing languages, much more so in case of C.