I'm currently setting up a brand new hosting server for a client of mine that owns a news site. One idea that was suggested by the team was to offload the Media Library files entirely onto a CDN. There is a plugin that provides this: https://wordpress.org/plugins/amazon-s3-and-cloudfront/
The plugin basically has you:
- Upload your files normally onto the Media Library
- The plugin will upload your file onto your CDN, then delete the file on your Media Library
At first glance, the concept of the plugin, as well as the reviews it has, gives me some concern. WordPress's core code is very tightly integrated with the Media Library, and even if the plugin works perfectly, I'm concerned that deleting the original files wholesale will cause issues with other WordPress plugins.
It is definitely safer if our CDN just replicates the file from the server. We are just exploring if it is possible for us to minimise the amount of data on our web hosting server.