Using the same code for the backend is not realistic since Clojure leverages JVM libraries. A new ClojureScript backend ecosystem would need to start wrapping Node libraris to reach Clojure parity
I did this late last year for a traffic analytics backend. As you said, I had to wrap a lot of Node.js libraries, and then wire them up with core.async.
It was a fun project, and I learned a lot, but I ended up reimplementing the whole thing in Clojure+Java because performance and DB access was so much better in this use case. Having only a single event thread kills Node relative to the top JVM servers.
