The problem with communism is there's no incentive to work. If I make the same working 80 hours a week that I do working 1 hour a week then why the hell would I work 80 hours a week?
Communism can be real, but only when no one will
have to work :)
For example, if nanomachine assemblers or some other cyber-magic can do all the production, mining (not the bitcoin mining :), recycling and so on. Then only research, art and similar activities will be left to humans. Some of them will do this because they like it anyway.
With current conditions it's, of course, impossible.
Even now I think that the non-creative job that needs more than ~10% of someone's time is a job for machine :)