I haven't heard of an offline wikipedia, and I'm not sure any wiki is ever "done." Entries can almost limitlessly be expanded and detailed, and at the current rate, it'll be many years (decades?) before a relatively complete chronicle will be compiled.
Is there a particular reason/use for an offline WC Pedia? I'm asking seriously, because "offline" can mean many different things. Is it just a zip of the page texts (which may not automatically work without the underlying database) for people who connect via dial-up internet? Is it for laptops/tablet computers for people to read on airplanes or long road trips (where internet access is now available)? Whatever form an offline wiki could take, it would undoubtedly require time on the part of our skilled wiki experts to set up, and I doubt it would be used for much. In that regard, I think the best use of people's time is probably to just continue to expand the online wiki for everyone.
So it's certainly possible, but why would we do it?