As long as the involvement of a lot of people is an important requisit for something to work, it will be wandering in the utopic limbo rather than the pragmatic one. If getting the required people together to be in favor of something good was easy task we wouldn't have kids that starve to death, etc.
I don't think you are describing what "utopic" is just what an "idea" is. If I am an architect with all the resources I need, I can plan a building and that is not utopic is just a model of something I know can be accomplished.
Best regards.
Sebastian.
Involvement of people is important maybe for everything the mankind ever made. Many of the things you see arround you are an evolvement of people. I don't think for example, that you built the town where you live - all of the buildings, the schools, routes, etc. Nor you have made all of the models of the cars - from the first to the last for all of the car companies. The idea, that a frozen corpse can be revived in the distant future, even if it was not frozen properly is both utopic and pragmatic before you proove without any doubt one of the above. To suppas the threshold, you need to make something utopically new to work, you need many people working for it, but the labour may be spread along the years. E.g. you may need the constant work of 1 000 000 people to make it happen for an year, or the constant work of 100 people to make it happen in ten thousand years.
How about when you make something that does not exist at all? Like patentng something? For example people from the past wanted to fly quite a long time ago. Much long before the firs air baloon. The people before the air baloon thought this idea of flying man is an extreme form of utopia. Now we know we can fly. There are passenger airplanes. Everyone can fly. Was (before the hot air baloon) the dream of flying utopia, since it is possible?
Same is valid for the cryonics. Its not working today. But there are people, who dream about it, and work for it, so you never know when the treshold of work and mind needed will be passed and the cryonics will become a reality. Corpses frozen now even unapropriately may be able to be thawed and revived in the distant future, if they somehow are available when the threshold is passed.