I don't think it is productive for any franchise to label any player as "untouchable".
Wayne Gretzky was traded. Anyone can be traded.
If a trade makes your team better or better positions you for a rebuild, then nobody should be considered "untouchable".
If some team wants to give you a couple of 1st round picks, or a 1st round pick and an elite prospect, for either Josi or Ellis, then you have to consider doing it.
They aren't going anywhere during the prime of those two players, so if you can start a rebuild by getting prime assets for them at the peak of their value, then you have to do it.
As for Rinne? I wouldn't consider him untouchable. More like "what would the point be of trading him?". I don't think you would get much for him. Goaltenders never fetch much of a return when traded. Some teams have trouble even giving goaltenders away for free. So they might as well just allow him to finish his career where it started.