It means something when the greatest rival for a lady's heart is no other than yourself, or an alterego, for that matter.
I absolutely love how this story is going. It has a great potential and I do have a few theories where it might be going. For example, this whole story's premisse is that the absolute and pure devotion can work as a source of power. Therefore, I think that Mao's/Shinome sensei's Manga events will start to become true, with Aiko's belief on it so powerful that everything might just happen. With that, other people will start to "convert" into worshippers of Shinome sensei's work, increasing it's power to influence reality and all. Maybe Mao revealing that she is the author to Aiko might weaken her dedication, but could also just increase it to a level never seen.
Really, I guess I'm also becoming a pilgrim. Wonderful work indeed.