Seems like the underlying format is unrelated to editing with customizable AST—in fact, that seems like it'd make things like code review pretty miserable. You'd have to upgrade all tooling to be ast-aware.

That said, once upgraded, that would be far, far, far superior to text. Our tooling hit the limits of text a long time ago: consider how terrible diffs are at communicating simple operations like indentation changes, or how basic our refactoring is even in the best case scenarios.