Reputability and reliability will absolutely take a deep dive.
The greatest asset of Wikipedia is not the trove of data (I have the copy on my computer), but efficient moderation, neutrality, and trust.
None of the clones are nearly as trusted, as they're edited at a whim of whoever owns them, or simply poorly moderated.

.zim archive, can be viewed directly via Kiwix for example, so can be stored as is