C coders will emulate Lisp features when required
When is this required? Cite actual examples, please.
The question is poorly stated
The question is stated specifically to avoid more examples of using Lisp to accomplish something within Lisp while having no effect on anything outside of Lisp. The earlier example of PROGN illustrates this well. Yes PROGN is great to have in Lisp. But in every other language you can simply write multiple statements in an if block without PROGN. So PROGN doesn't actually accomplish anything and certainly doesn't provide an "open future". Eval is another good example. Yes Lisp allows us to Lisp while we Lisp, but why does that matter? What can we accomplish with this in real terms? It is telling that within this constraint you cannot give any examples of Lisp's superiority to C.
Have you tried to make a web site in C?
https://kore.io/
https://facil.io/
https://kristaps.bsd.lv/kcgi/
Have you tried to make a website without C? This website runs behind a reverse proxy written in C on an OS written in C.
Where's that smartphone app written in C?
https://developer.android.com/ndk/guides/stable_apis
All Android apps run in an environment(ART) which is written in C.
What real world tasks can C do that Lisp cannot?
C can run efficiently on a wide variety of bare metal architectures without the overhead of hosting a compiler/interpreter/kernel/whatever.
The real wonder of Lisp is how it transforms your thinking about programming
This may be the case, but this is not what's being claimed here. What's being claimed is that Lisp is a secret misunderstood bastion of capability that the whole world is overlooking in favor of the "strangely limited" C.
If we want to abandon Minsky's claim of Lisp's "open future" juxtaposed with C's "strange limitations" and instead focus on Lisp's mentally transformative nature... We're going to need some actual examples of that, too.