Yeah, I'm thinking that any profunctor \$$X \nrightarrow Y\$$ can be flipped to give a profunctor \$$Y^\text{op} \nrightarrow X^\text{op}\$$, because \$$X^\text{op} \times Y \cong (Y^\text{op})^\text{op} \times (X^\text{op})\$$... so, um, something something duality... (bit too tired to think this through right now!)