Individual cells or very small groups of cells such as an early embryo can be easily frozen and succesfully thawn after decades, and probably after a nearly limitless amount of time if storen properly (e.g. in liquid nitrogen or colder).

However, currently there are no means to cryogenically store bigger animals, not to mention warm-blooded mammals such as humans. Uneven distribution of cryopreservants, uneven freezing/thawing speeds and the complexity of systemic functions such as respiration, circulation, digestion and central nervous system make it absolutely impossible – with current means that is.

Furthermore, if this was possible in the future, I’m pretty certain that anyone cryogenically preserved today could not be revived in the future, because our current technology would only result in systemic necrosis due to extreme cellular damage the freezing causes.

we do that with bacteria, yields are low

Yeah, bacterial cells are more robust; you can get some live cells even if you store them without cryopreservants (or cryoprotectants). With animal cells, you need to add something that prevents ice crystal formation, the most common ones being DMSO and glycerol.

Also, some small invertebraters such as tardigrada (water bears) use the sugar trehalose to prevent ice crystal formation, and thus they can survive even if they were throughly frozen and then thawn. Trehalose synthesis and other metabolic changes take some time, though, so your water bear will not survive if you simply drop it into liquid nitrogen.