Hi Mary,
The JW stance on blood transfusions has little to do with the bible, and, as Grace and others have said, is about control, pure and simple (though not very simple for JW's). The corollary is therefore in the case to which you allude is that thier beliefs in this regard are founded on rather shaky principles and grounds, therefore they have a harder time justifying control in this instance, and any smart JW will be alert to any lacuna(e), and accept treatment, if appropriate.
Going on from this, the whole field of regenerative medicine is in its infancy ( no pun intended) and will transform therapies for a very wide range of diseases. I attended a lecture at my older son's University, Kings College London, which was full of people doing research in this area from all over the world; the guy I sat next to said to me that he fully expected people to live 40 years longer in 20 years time, that was 4 years ago. There is hardly a week that goes by now without an article in the news about something to do with it, like the article which you introduced above.
The biomedical ethics, and jurisprudence of such therapies is a little way behind the science.
David