If there were a candidate for another official Gremlin driver, I'd say that it would have to be Go. I've heard more requests for official support there than anything else. As far as I know there are no less than five different third-party Go drivers out there right now which further leads me to believe that folks want this functionality.
I do have concerns about the additional overhead of yet another programming language to support, but if it helps unify a programming language space where we have a large number of users who would benefit, it's probably worth considering. Happy to hear from anyone with thoughts about adding support for Go, experience with any of the third-party Go drivers out there, etc.
