If you’re inventing new syntax... Wouldn’t an a async/await be more useful - to declaratively indicate the desired dependencies between simultaneously operating statements? That way you can work with the results of an inserted PK or the row count to inform later statements - when needed. Eg. ‘returning async’

I believe this suggestion came up at the time. I think we didn't do anything like it because it would have been more complicated both to implement and to describe, and because it's not particularly common for people to use/need the values that can be returned by the statements that we can parallelize. The future, though, is long and open.