When you talk about the future of primary education, it's worth examining what's going on with professional training. The U.S. training market is a $100 billion + market annually, and a large portion of that ($30-$40 billion) is already online (citations all here: https://www.opensesame.com/blog/everything-can-be-digital-will-be).
Factors driving this adoption:
- content is becoming fungible (I work for OpenSesame.com, which is a marketplace for online training - like iTunes for education)
- more nimble customers have driven faster market development
- there's a (mostly) effective software standard for corporate training content - to ensure content works across platforms (this is SCORM - see scorm.com for more info)
The lack of an effective standardization for content has made cross-use of content across platforms (in a way that tracks) difficult.
I work for OpenSesame.com, a B2B e-commerce marketplace for online training courses. We can shed some light on the challenges B2B marketplaces face. First, it has been challenging to explain our business model to some customers who are used to shopping in marketplaces like the App Store and eBay in their personal lives, but not so much in a professional context. Second, even though we're operating in a $100b+ market (corporate training), we have also found it difficult to attract attention from blogs outside of our specific industry niche. The B2B market is more complex and less "sexy" - but there are tremendous opportunities for startups to disrupt entrenched, dominant vendors.
This is a particularly hard problem for community-based sites like Quora- in part because the "in-crowd" can be unwelcoming to the newbies and in part because it turns into a huge time-suck for the startup's own team, both community and technical. The more of an "in-crowd" feeling you create, the harder it is to grow - and in that case the community and the founders' interests are not aligned. Community wants their tight-knit Cheers-like bar feeling and the founders want expansive growth (usually). Tough problem to solve.