Morimoto is a candidate. Same type of roots as Iwata (just from GameFreak, rather than HAL). And he took over the Japanese directs, so he's been working closely with Iwata as of recent and I don't doubt Iwata had the foresight to plan out his succession given his health.
Agreed. Morimoto has sort of seemed like Iwata's protege of late. When he introduced Morimoto as taking over the Directs from time to time, alarm bells did ring in my head :/