SQL is a fantastic set based language. Using SQL to query MongoDB would be about 7 steps forward for just about everything I do, particularly if "SQL" magically included joins.
I'd say forward for sure. This breaks down the barriers to entry for a lot of folks, especially in enterprise land. Definitely looking forward to how this develops.
I think it makes a lot of sense for the document databases. It would make much less sense applied to something like Redis though.
Yeah... Redis could probably use a subset of SQL, though, but I don't know if it would be practical.