The original dichotomy is correct if you think about the consequences of cryonic success.
IF and only if cryonics succeeds, the world had developed the technology to restore you from a cracked, solid mass of brain tissue. (the liquid nitrogen will fracture your brain because it cools it below the glass transition point)
Also, as sort of a secondary thing, it has figured out a way to give you a new body or a quality substitute. (it's secondary because growing a new body is technically possible, if unethical, today)
Anyways, this technical capacity means that almost certainly the technology exists to make backup copies of you. If this is possible, it would be also possible to keep you alive for billions of years, or some huge multiple of your original lifespan that it could be approximated as infinite.
You might consider these technical capabilities to be absurd, and lower that 5% chance to some vanishingly small number like many cryonics skeptics. However, one conclusion naturally falls from the other.
growing a new body is technically possible, if unethical, today
We don't know how to reliably clone a human being, and we definitely don't know how to transplant your brain into it or attach your head to it.
If you don't believe in an afterlife, then it seems you currently have two choices: cryonics or permanent death. Now, I don't believe that cryonics is pseudoscience, but it's still pretty poor odds (Robin Hanson uses an estimate of 5% here). Unfortunately, the alternative offers a chance of zero. I see five main concerns with current cryonic technology:
So I wonder if we can do better.
I recall reading of juvenile forms of amphibians in desert environments that could survive for decades of drought in a dormant form, reviving when water returned. One specimen had sat on a shelf in a research office for over a century (in Arizona, if I recall correctly) and was successfully revived. Note: no particular efforts were made to maintain this specimen: the dry local climate was sufficient. It was suggested at the time that this could make an alternative method of preserving organs. Now the advantages of this approach (which I refer to flippantly as "dryonics") is:
There is one big disadvantage of this approach, of course: no one knows how to do it (it's not entirely clear how the juvenile amphibians do it) or even if it would be possible in larger, more complex organisms. And, so far as I know, no one is working on it. But it would seem to offer a much better prospect than our current options, so I would suggest it worth investigating.
I am not a biologist, and I'm not sure where one would start developing such a technology. I frankly admit that I am sharing this in the hope that someone who does have an idea will run with it. If anyone knows of any work on these lines, or has an idea how to proceed, please send a comment or email. Or even if you have another alternative. Because right now, I don't consider our prospects good.
[Note: I am going on memory in this post; I really wish I could provide references, but there does not seem much activity along these lines that I can find. I'm not even sure what to call it: mummification? Probably too scary. Dehydration? Anyway feel free to add suggestions or link references.]