They're just a private, more efficient network than the internet. I wouldn't really call this proprietary lock-in - they just accept and deliver packets over IP

They're just a private, more efficient network than the internet. I wouldn't really call this proprietary lock-in - they just accept and deliver packets over IP. There should be lots of these networks (admittedly, there aren't...). If anything, this Cloudflare Network Interconnect thing makes them less proprietary. Now you are on the same playing field as the services hosted inside their own network - you could, for example, set up your own network of datacenters and make your own CDN on top of the Cloudflare network.