Like any great idea, it's all about execution. This can be awesome, and can lead to a consolidation of many different voices regarding the storyline. Which in turn leads to either a damn good read or healthy discussion.
That being said - the format and means of contribution is more tricky. It should provide consistent exposure to all different angles on any particular subject, yet consider allowing for further discussion and scrutiny aka "im right and this is why you're wrong".
The "discussion part" can take back from the collaborative energy of such a project, but perhaps can be isolated to forum posts and allow for healthy debate; the top posts (either through discussion volume or unchallenged data) regarding a certain topic (character, item) can be a part of several brief "suggestions" or "speculations" that can make their home at the bottom of a wiki page.
Ex. on
http://darksouls.wikidot.com/solaire-of-astora
- underneath Dialogue we can fit in "Lore" or "Speculation" section - or even insert as spoiler tag footnotes. These are just off-the-hip suggestions, I'm sure we can brainstorm.
This could set a good precedent for the release of the upcoming game Dark Souls 2. Dark Souls has been out for some time now, and the feverish discussion on lore that the community has enjoyed may be slowing down a little bit. Nonetheless I can only see good things coming from it if the thought and effort are put in.
As long as we can always find somebody to disagree with, we're in good shape.