Well, they're starting human trials for short term (<2 hours) suspended animation at cool, but not subzero temperatures (5-10c). It's worked in pigs and dogs, so it's expected to work in humans. Going beyond that, however, is a problem, because the cells are still alive relying on stored energy to metabolise at a very, very slow rate, such that they survive hours instead of minutes. Find a way to replenish those stores, or increase them, and you might be able to drag it out to weeks and months...
As for the age of majority, I expect we already have precedents, since children do fall into comas some times.