This is where things get incredibly weird for cryonics. Any competent practitioner is going to amass a large number of people who are legally dead today, but may be viewed as "just sleeping" in the future. Where is the boundary between these two states? At what point do these frozen brains transition from specimens with no rights to human beings?
Say that, in the not too distant future, the technology is invented to resurrect the frozen. At this point, the cryonics company will have something clearly different from medical specimens in their tanks. However, what if the resurrection tech is prohibitively expensive? Even at cryogenic temperatures there is atomic movement and, necessarily, slow and subtle degradation. Some frozen "sleepers" might not survive long enough for resurrection to become affordable enough for them, assuming the assets they set aside for resurrection weren't wiped out by bad investments. Do these doomed sleepers have any rights? Will the cryonics company be obligated to revive them at a loss? What if the company goes bankrupt? Could people be brought back as indentured "heads in jars" and expected to work off their debt? Will brains frozen today even have any skills or knowledge the future will want?
Cryonics raises a lot of questions for the present and, potentially, even more problems for the future to solve.