I am watching Stargate universe (SGU) again, why not, and they make extensive use of the "communication stones".
These allow two people to swap bodies over any distance. There is a device that handles the stones, and they can be disconnected. Interestingly the link is disrupted when one end going in to, our out of, FTL (Faster Than Light) travel. The connection breaks totally if one side goes through an intergalactic gate...
One of the odd things on this plot device is the issue of what happens if someone dies?
The plot is that normally there is no physical effect on one side yay effects the other, so lack of sleep, caffeine, food, etc, does not impact the other person, but death and near death does! If one end dies, both die.
I was thinking, why would this be? The mind swap seems pretty absolute, so one end dying should leave the other end stuck in a transferred state, surely?
Well, I forgot the Terry Pratchett narrative imperative...
If the communications stones allowed any way for the swap to be permanent, even with one party dying to make it so, it would create a massive plot device. Any person can extend their life by simply swapping with a younger person and then getting killed. It would break the normal flow of most fiction - you cannot easily have immortals in a story line (Dr Who excepted).
So that is why both ends have to die, no matter how illogical that may seem.