>>25345471The games turning out not to be the Kalos Pentagon games, or, you know, actual footage. If we see footage of the gameplay and it looks significantly different from Gen VI, then it's a new gen. If it and the battles look the same as XY/ORAS, along with the same model appearances, animations, etc then it's still in the same gen.
People are using the ideas of new Pokemon to confirm it as a new gen but I don't think that would work, seeing as Gamefreak has proven with ORAS that the don't care about compatibility within the same generation.