I think if Roland's body had died, the Roland would continue to live in Eddie's body. I can see why a person might think that he would die though, after all how much of a link remains between the body and 'mind/spirit/ka/whatever/' when it's vacant?

I think it depends very much on how 'there' the individuals mind actually is. In this case, I would say totally (taking into account he felt none of the sickness of his body or the dulling of his senses when in Eddie), hence my conclusion.

Wolves of the Calla spoilers:


Consider this though:
Spoiler:
What if the person had gone todash however? You know, when it fades in and out of existence? I think if the body were killed in that state, then the person is completely dead. Then again that form of todash is different from the mind possession that occurs in tDotT, as the body itself is partially 'there'.