It would be interesting if the de facto hierarchies arose entirely by bottom-up merit (not, say, approval from above), and were flexible and ephemeral, not self-perpetuating.

People could self-organize, on-demand, for a task, and structure whatever hierarchy was appropriate, based on somewhat optimal resource allocations for that task.

(Example: Person A might normally be the most experienced at facilitating the group's coordination, but A is providing key technical expertise for this task. Person B isn't critical path on this task, and has facilitating skills and interest in that role, so B volunteers for that role for the duration of the task.)