I couldn't find a date on this essay, but it must have been written around 10 years ago. The open source Common Lisp ecosystem, though still small, is much larger than it was then. (For instance, he doesn't mention SBCL or OpenMCL/Clozure CL in his list of open source implementations, and he claims there aren't any with multithreading, which hasn't been true for years.)

So if he still misses Lisp, he should come back. Common Lisp is still around, and in better shape than it was, and there's also Clojure.