[yason]

having it no longer an essential part of the curriculum makes it much, much less likely to be learned or used

I argue that it's likely that Lisps are mostly learned and used regardless of any curriculum. In order to "get" Lisp, you have to be both endlessly curious about computing and in need for something that offers the benefits of a language like Lisp.

You will not "get" Lisp merely by being taught Lisp; you're only likely to be left with the question "Why?" until you actually need something like Lisp and can answer the "Why?" yourself.