Got any specific details of how this makes hosting more expensive and difficult to scale? If the browser and all web servers have the same certificate, I don't see much of a challenge in going SSL-only.

Also, I did some research after posting. Google Chrome now has an HTTPS-only mode: http://www.cgisecurity.com/2009/01/httpsonly-mode-added-to-c...

And the EFF has released extensions for Firefox and Chrome that apply HTTPS to all websites: https://www.eff.org/https-everywhere