Theoretically speaking, in a future where the world runs itself and all notions of "scarcity" are eliminated by energy, technological, and agricultural abundance, what need would there be for capitalism, let alone money?
And if the economical system would be a pure capitalism, we'd get there anyway, but unfortunately people feel the need for government regulation, which produces more scarcity and monopolies, ultimately hurting innovation (e.g. DMCA, DRM, patents, or my recent favorite, Net neutrality).