> if a decent looking/working e-mail client with end > to end encryption appears...

  > if a decent looking/working e-mail client with end
  > to end encryption appears this year, I'll move to it
  > almost immediately.

Thunderbird and GPG work with Gmail today.

  > So if Google wants to keep me as a Gmail users,
  > they'd better enable the DarkMail protocol [1]
  > or something similar in their e-mail client.

Gmail doesn't have a desktop email client. If encryption were added to the Android clients, then the web interface would become useless and the whole point of Gmail (being a web-based email system) would be moot.

  > As soon as TextSecure is fully cross-platform,
  > I'm switching completely to it.

The TextSecure wiki[1][2] describes a fairly wonky encryption protocol involving two shared symmetric keys instead of using public key encryption, so I have little confidence in their system's ability to withstand analysis by state-level actors. You're better off using GPG and email.

[1] https://github.com/WhisperSystems/TextSecure/wiki/Protocol [2] https://github.com/WhisperSystems/TextSecure/wiki/Using-Text...