Chris Melandri of Illumination Entertainment is the primary driving force behind the sudden influx of Seuss-inspired movies, as Deadline explains: “Meledandri started the relationship with Mrs. Geisel and the estate of her husband when he ran Fox Animation and made Horton Hears A Who there. He brought over the relationship when he agreed to start a family film division for Universal.” It’s nice to know that if these adaptations are indeed to continue happening, that they are at least happening with the agreement and assistance of the Geisel estate.
The same article by Deadline also mentions that the live action/animation hybrid movie about Theodor Geisel starring Johnny Depp is still very much in active exploration and development.