10 Hygiea is a spherical body in the main asteroid belt. With future telescopes like the Vera Rubin LSST or the James Webb Space Telescope, can we determine whether Hygiea is actually in hydrostatic equilibrium, or do we have to send a probe? For the IAU to classify a body a planet or "dwarf planet" it must currently be in hydrostatic equilibrium. Could we (dis-)prove that on Hygiea with the telescopes to come?
Does really nobody know? I suppose the answer is "they might determine it" then?