It's just an offhand remark by you, but I think it's a very good idea. Wikipedia is quite hit-or-miss, but right now it's at least the equal of any traditional encyclopedia we had in the old days.
But if there's no power and no technology, how do you view your offline copy? At least books have the potential of surviving for hundreds of years w/o too much degradation.
Add some decent solar power to that, and scavenge for spare parts to keep it going, and I plan to be running a First Foundation / Oracle of Delphi pretty shortly after civilization collapse.
I was surprised by the vividness..