In case you couldn’t tell from the title, I’m going to outline the way I think LEGO could bring back Bionicle not just for fans of the theme and LEGO itself, but even possibly attract a whole new audience as well. Before I delve in I want to say that this whole idea is based on ideal conditions.
Okay, here is my idea. Comic books.
LEGO can start a G3 continuity with comic books almost like Marvel and DC. This can also be used to continue G1 and G2.
What they could do is partner up with Marvel or DC (they already have partnerships with them for the Superheroes themes) and establish a panel of people to oversee comics being published in the Bionicle name and approve them. This can also allow new characters to be created quite a bit easier than how it used to be. It can open up the theme more to fans who want to be able to contribute something meaningful to the theme.
Combine this with making Bionicle sets with system Lego (with special constraction sets every so often) and we could get scenes recreated from those possible comics, just like the Marvel and DC themes.
This is just the basis of my idea and if you want me to I can try to elaborate. Let me know what you on this idea.