It's hard to imagine that OCaml's libraries/tooling would be the game changers (drop in the bucket by comparison to the vast JS ecosystem). Would be nice if SMLtoJs compiler got the corporate backing though.
OCaml has pretty good and modern tools (opam, meriln, oasis) and basically all the libraries you would expect, compared to SML which has no editor support, a very minimal stdlib, no package manager, no build system, very few and hard to find libraries, etc.