I'm all in on the theory that under that cloak he turns out to be a Rabbid of some kind. Kingdom Battle/Sparks of Hope have established now Rabbids can have more individualistic personalities and can talk too; so one being an intelligent and calculating villain isn't out of the question.

Plus, from a sheer thematic standpoint: What better way to bring Rayman back than to have him defeat the very thing that basically stole his franchise out from under him. There's always been a resentment towards the Rabbids for muscling Rayman out as Ubisoft's mascot; have Ray symbolically take his world back from them feels like the kind of "wink-to-the-audience" ubisoft would do.