I agree with lots of the points here. However one of the great strengths of the SQL family is the FOSS history. I doubt something proprietary is ever going win everyone over. At least I hope not.
SQL took a long winding road to reach the FOSS friendliness it has today. Its history is littered with patent, copyright, and trademark disputes. Not to mention widely varying implementations and the continuing lack of a crossplatform wire protocol or standard interface. Proprietary incumbents still dominate huge sectors of the SQL landscape and pose compatibility and intellectual property issues for FOSS implementations.
I think any SaaS APIs that reach any degree of widespread adoption eventually get OSS implementations (eg S3's API is widely supported by FOSS and proprietary implementations). This evolutionary path is awfully similar to SQL's for better and/or worse.
Awesome! This is a great article. I've been thinking lately about how ORMs are basically a band-aid meant to fix the weaknesses of SQL, so it's great to see people trying to solve the problem from the bottom up.