There is a lot of loose terminology being tossed around here. Wikis are not "dead" simply because no one is editing them. Some articles might be getting stale and new articles might be missing but those factors do not mean a wiki is dead. A wiki is only truly dead when it is not visited by anyone on the web or it is taken offline.
Here is the Wikipedia page for dormant articles. Many of these articles have not been edited for over 7 years. Are these articles dead? No, they just might be in need of updates. I'm sure lots of them have been used millions of times in those 7 years by those searching the web.
With that said, I still think the Nintendo Wiki has a strong reason for existence. There is plenty of information about Nintendo which is not series related.
Nintendo and its corporate history
Important Nintendo executives, Shigeru Miyamoto, lots of others
Nintendo hardware and peripherals, where else do articles about the Power Glove, Super Scope, and Virtual Boy go?
Development studios which Nintendo controls and their history
Games which do not merit their own standalone wiki (Wii Sports/Play/Party/Music, Game and Watch, other Nintendo ventures which were Japan only)
The Nintendo Store in New York
Channels on the Wii and Wii U
Nintendo Power magazine history info, etc
Nintendo @ E3 (I think it would be awesome to have articles detailing what Nintendo unveiled each year, reaction, etc)
Nintendo is identified by the products it makes, which is why the Nintendo wiki is really a "support" wiki to the game series wikis. I don't believe it is dead or useless though.