I'm using TB since two years, when Apple Mail failed to load after an OSX upgrade. I wanted to move, preparing for moving to Linux later on. I have several family members using TB on Windows. My mother used Eudora for years, I believe seven years after development stopped. It never had a problem. I could copy it to Windows 7, just copying the folder with the program files in it, and it all worked.

How big is the risk if TB development stops altogether? What security risks are there when you keep using it?

My mother cannot handle changing to something new anymore. So I guess I have to take the risk.