And also, IIRC, rumor has it Google attempted to acquire Wikipedia a long time ago but was rebuffed for this very reason.
Google could certainly just give them a lot of money, and possibly get a board seat.
It'd be even more problematic in this case, because the Foundation's mission statement explicitly promises to maintain these resources "in perpetuity", which would seem to conflict with selling them to a third party:
In collaboration with a network of chapters, the Foundation provides the essential infrastructure and an organizational framework for the support and development of multilingual wiki projects and other endeavors which serve this mission. The Foundation will make and keep useful information from its projects available on the Internet free of charge, in perpetuity.
It's possible there's some legal wiggle room around that, but it would certainly seem hard to justify.