All turing complete languages make anything possible, right? The only question there is whether or not you detour through Greenspun's Tenth Rule to get where you're going.
I think Steve's point about Clojure having a limited time to gain acceptance before it's considered "over" is valid, even if he doesn't necessarily show us a way out.
Programming language adoption happens one developer at a time. If the silly TIOBE index is one's preferred benchmark, it's worth noting that every single language in the top 50 has been around for decades (with the exception of Go and F#, which have generous and powerful corporate sponsors).
I think Steve's point about Clojure having a limited time to gain acceptance before it's considered "over" is valid, even if he doesn't necessarily show us a way out.