These third alternatives you talk about are too new. None of them were more probable than the immortal soul 50 years ago. Most people have not yet adjusted to derive hope from these alternatives, even if they do seem to be marginally more practical now. The other problem is that success or failure of these technologies is apparently in the hands of fallible human operators, but the soul is outside human control altogether. Perhaps, people are afraid to trust other people with their "eternal" life.