Communism as it is practiced in the real world has no bearings on the true definition of communism. The system you described reminds me much more of a socialist state than a true communist one. In true communism, it is eventually possible for the government to actually become a figure head, only keeping crime at bay and not really interfering with economy. What you call profoundly anti-communistic is the very goal that true communism reaches for.
Manufacturing for no cost will actually be possible, at least in the not extremely distant future. Think about it. Once fusion power becomes safe and possible, a generator fueled by hydrogen, which it can easily obtain from two of our most abundant resources, air and water, can be practically turned on and left alone and will power cities or even continents ad infinitum. Your energy problems are solved. And with the increasing development of nanotechnology, perhaps replicators aren't that far off either.
Finally, if you think technology will not reach these levels in the next hundred years, think again. I remember buying a computer in 1993, and Pentium 90's were just coming out. We have gone from trying to break the 100Mhz barrier to making 1.5Ghz processors in 8 years. Now tell me technology is moving slowly.