PGP has sound fundamentals, I wouldn’t count it out yet, the problem is with key distribution and mail client integration. No major webmail provider supports it for various reasons, and that’s a huge blow for making it generally usable, because the majority of people use webmail these days.
If Google figured out some way to integrate it with Gmail (encryption/decryption handled by JS in your browser? JS in browsers has a pretty checkered history with security…), then this would become a much more reasonable solution. This would undermine Google’s business model though, so it’s probably not going to happen anytime soon, not unless they get really really mad at the NSA for spying on their internal networks.
