A similar idea is to allow pages to download static content over HTTP if they include the hashes of the content. Things like CSS and javascript need authentication so you know they haven't been tampered with, but don't necessarily require encryption. (The authentication here is from the fact you would download the page containing the hashes via HTTPS). Using this to download the global static content for a site doesn't even leak which individual page you were looking at.
On the other hand, it complicates things a lot without really giving much advantages. The only time I can think of where it might be useful is for using CDNs from a HTTPS site, without having to set up HTTPS with your CDN.