I already have a number of ways to sandbox in the browser I'm most comfortable using. The place where I'm most theoretically concerned with this is actually on my mobile devices, but given the way mobile operates, I'm not sure it's even remotely possible to have truly private communications using devices from any major platform.
It has. I can't provide hard links, but Snowden's revelations pretty much confirmed it - I remember reading about it with dismay.I suppose PGP is likely to also have been compromised and that I just don't know about it yet.