And I'd argue that google's about the only thing propping up the internet. Chromium's a reasonably open platform (certainly more so than internet explorer, which not that long ago looked destined to become the dominant platform), gmail has kept email viable, android is somewhat open (and without it, apple might own that space entirely), etc
Every other player that's gotten traction has set up a walled garden
In fact it's exactly the same reason why Mozilla is increasingly not sustainable. Email hosting is simply not a lucrative business. That's why it's all run by large portals like Yahoo, Google, Microsoft, etc. which use them not to make money but to collect information about people, and monetize through ads or other indirect methods. Of course, this only becomes profitable at scale, and there are not that many companies at that scale.
As for Mozilla not being sustainable: I think they could be, but not the way they run their business.
Email hosting is lucrative enough for Fastmail.