  The holographic entropy cone identifies entanglement entropies of field
theory regions, which are consistent with representing semiclassical spacetimes
under gauge/gravity duality; it is currently known up to 5 regions. We point
out that average entropies of p-partite subsystems can be similarly analyzed
for arbitrarily many regions. We conjecture that the holographic cone of
average entropies is simplicial and specify all its bounding inequalities. Its
extreme rays combine features of bipartite and perfect tensor entanglement, and
correspond to stages of unitary evaporation of old black holes.
