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: