> The proposed enhancement would provide a complementary function, `dump_json` as in a json representation of the ast. 

IMHO this is not a feature that has a general usage. If you want, as far as I can see, there are some packages for doing that in PyPI already. Also, the patch looks small so you can just add this to the required project.

> This would be useful for those who would like to benefit from the utilities of the json module for formatting, pretty-printing, and the like.  

ast.dump now can dump in pretty-printed way.

> It would also be useful for those who want to serialize the AST or export it in a form that can be consumed in an other programming language.

As I said, serializing/exporting the AST isn't a common use case. It is a very specific goal.

In general, I'm -1 on this.