I don't think "critical updates" are really that necessary. Swapping SD cards a couple times a year would solve most of it. I think it's pretty incredible (and useful) to to be able to have access to all that information for such a low cost even if it's a few months (or even years) out of date.
Depends what you mean by copy. If it's just a static data source, any offline project would do it. If it has to update it's trickier, but some offline projects do it too. If you want to run a full clone of Web's fifth popular website, yes, it requires some effort. Sorry, no magic here :)
> "can plug in and go through the configuration wizard for a NAS/router/streaming box."
There are boxes that are integrated with one or another of the offline projects. There's also Wikipedia Zero - which in the world where mobile coverage is becoming more and more widespread even in poor regions, may be even better alternative.
That doesn't come close at all, from the perspective of a librarian who wants a "copy of Wikipedia" for their library, no? It assumes a ton of IT knowledge, just from the point where you need to combine software with hardware with database dumps.
The average library staff who'd want to set this up in some African village would be less on the side of the knowledge spectrum of "knows what to do with a VM image", and more toward the side of "can plug in and go through the configuration wizard for a NAS/router/streaming box."
Once I can tell such a person to buy some little box with a 4TB hard disk inside it, that you plug in, go to the URL printed on the top, and there Wikipedia is—and then it can keep itself up to date, with a combination of "large patches that get mailed on USB sticks that you plug in, wait, and then drop back into the mail", and critical quick updates to text content for WikiNews et al that it can manage to do using a 20kbps line that's only on for two hours per day—then you'll have something.