I would much rather see effort made by google to provide two backends datastores. The existing (primarily) key based bigtable, as well as true relational database. Ideally they could even provide the relational DB service where users would need miniscule knowledge for basic DB administration (replication/backups) and simplified administration for sharding. Ideally if the there was a way for the records to be cross polinated, even better.
I doubt that will happen any time soon. Apparently, relational databases don't scale very well.