I didn't read the entire thread, but I disagree with the OP.

Anonymous for example can be considered an anarchist organization in the sense that there is no central leadership or hierarchy. However, this does not prevent the forming of cells and networks that have their own internal hierarchy. I see anarchy as the freedom to join a system that you feel works best, without being forced into a system - rather than being forced to have no system at all.

While this may be stretching the definition of anarchism a bit, I feel that a society that works with 'cells', where every cell has its own structure (be it communist, socialist, or anything else), and the only rule was to not actively interfere with other cells and their structures... would still fit the definition of anarchism, and would definitely have a chance of working.

It would be considerable different from communism, where everyone is forced to adhere to a centralized communist system.

And before people ask - yes, 'humanity/mankind' as a whole could probably be considered anarchist.