>  I would be pleasantly surprised to see code written today still compile
  > in five years.

That's the goal, modulo soundness fixes. We don't currently have any plans for a 2.0.

  > what will happen to Rust if Mozilla changes strategies

Well, we're just starting the process of integrating Rust code into Firefox. Yes, Mozilla has killed off a lot of things, but I don't think Firefox is going away any time soon.