Before revision:  Finally we write out expressions for the convex quartic locus of the incenter for a generic Poncelet family, conjecturing it can only be an ellipse if the pair is confocal  .
After revision:  Finally we write out expressions for the convex quartic locus of the incenter for a generic Poncelet family, conjecturing it can only be an ellipse if the pair is confocal , i.e., within a 1d subspace of the 5d space of ellipse pairs which admit 3-periodics .