It certainly needs a CEO/Visionary, it most likely needs HR and front/back office folks, it certainly needs PR and marketing people. But in a world where people communicate rarely in person, have their own management and economics 101 abilities, are smart enough to not work against their own interests (and look after the org's interests) - what's the role of the future manager?
It sounds inevitable that senior Engineers will double up as managers for their group as and when required (working with marketing etc.) instead of it being a dedicated managerial position.