I was talking about this procedure with mk tonight and I mentioned that the fusing of the spine is the one big hurdle preventing it. I used the case of a quadriplegic benefiting from a head transplant and then he said, "why wouldn't they just fix his spine at that point?" -Becasuse at this point, they would have figured out how to re-fuse a spine, right?
In its current form, you could use this technique to keep a quadriplegic alive whose body/multiple organs systems were failing. Long term, with the way medicine is going I don't see much use for this kind of surgery. In the next few decades we'll just make you a new bit, rather than taking an old bit from someone else and forcing it to work with immunosuppressants. However I still think it's a worthwhile use of resources because of the possible benefits for the treatment of spinal cord injuries.