If We Decentralized Everything, Do We Get Communism?

No. Well, not quite. Decentralization means voluntary associations and voluntary hierarchies instead of coercive central command. Some people may choose a communal form of association instead, others a market form. The market and its information network of prices is arguably far more decentralized than a communist central planning committee. Where there is a business hierarchy, employers must offer an exchange the employees value enough to make it mutually beneficial.