I can't help, but think that most of the theories that are arising in the Bionicle Discussion/Bionicle Theories Forums are heavily related to Bionicle 2015 being a huge similarity to the Old Bionicle Story.

- Like, the Skull Spider's behaving like Krana.

- The "Ancient City" appearing to be a dilapidated version of the present Okoto Island (and possibly floating). Eg. Metru-nui.

- And of course finding golden masks, which is the the most obvious one.

But what if it all comes down to the that fact that maybe LEGO isn't going to go into some real intense back-story? And most of these hopes and vibes for a real deep story aren't something we should be worried about?