I basically agree with everything you wrote, but for two subsidiary points.

1 - it's a phenomenal development platform. I have on multiple occasions built large systems later deployed, for the reasons you discussed, via C ports. It didn't nullify the work done in Lisp: we learned a lot, and quickly; were able to do quick experiments, etc. But ultimately we needed to join the wider world.

2 - there is / has been a sea change in the software deployment model; it includes web browsers, even more rapid and more flexible development etc. Clojure is a good example and consequence of this change. It's quite possible that the circumstances that led to Lisps decline (though was it really ever "mainstream?") may swing the tide the other way. E.g. "Rapid development and realtime deployment of lisp-based microservices" to agglomerate some popular buzzwords.

FWIW: I was a developer from MACLISP to MIT CADRS, various Symbolics machines (at one point I had two 36xx machines on my desk with color monitors attached) and various D machines. Right now I'm doing my development in C++ though.