The kind of communism that Jesus taught would make for a good world to live in. But it could only work for a group of people who freely choose to live for each other. Volunteerism combined with enlightenment.
So technology isn't the key, but rather spiritual awakening. Technology is a double-edged sword. And democracy has no place in an enlightened society. It is the will of the majority forced upon the minority, regardless of wisdom or morality.
As long as there are centralized power structures, self-centered power-hungry types will eventually take control. Greed per se is not the problem but rather the desire to dominate and control. Centralization favors the predators and psychopaths in society. Decentralization is the best antidote. Nationalism vs. Globalism. States rights (10th Amendment) vs. federal domination.
With enough local autonomy, groups of like minded "enlightened communists" can form as examples for others. Example: Amish communities. But there could be a technological equivalent of the Amish with local energy production, local manufacturing (3D printing), local everything..