A future medical technology based on a mature nanotechnology should be able to preserve life and restore health in all but the most extreme circumstances. Tissue preserved at the temperature of liquid nitrogen does not deteriorate, even after centuries of storage. If current medical technology can't keep us alive we can instead choose to be frozen, with the expectation that future medical technology should be able to both reverse the freezing injury and restore good health. A common misconception is that cryonics freezes the dead. The major reason that cryonics is not more favorably viewed in the medical community is relatively easy to explain.
Medicine relies on clinical trials.
The appropriate trials can be easily described. Wait 100 years. See if the technology of 2100 can indeed revive them. If a new treatment is being tested we normally have the results of animal trials and perhaps some preliminary results from human patients. Further, we expect to get reliable results within a small number of years.