Don't think so, he stated one of the most important reasons was code compatibility, not specifically a good concurrency support (but this was important, indeed). I think even the most functional languages would not be easily compatible with "functional typescript code" without hard modifications. But either way, there is space for innovation in the field, I'm yet to see a ML-family language with concurrency that is as "hands on" as Go is, it would be extremely interesting to see this happening.