I remember a couple of weeks ago someone showed their project which was a "personalized" version of StackOverflow: You hired one hour or so of a developer to help you solve an issue.
The problem I see with StackOverflow is monetization: They tried with Ads (which have slowly been rejected by society). They tried as a candidate sourcing service (I used them to hire a long time ago, and it didn't have good Signal to Noise ratio). Then they tried with "StackOverflow for work" which I think makes sense for very large companies (think Oracle, IBM or similar size) but not so much for SMEs.
I would love to see them test-drive a micro-transaction mode where they ask people viewing a Q&A page for a small fee (think $0.01) to view the responses, and they could even share the revenue with people who write accepted/updated answers. This could be an interesting use case for something like Neo, Nano, IOTA or Ethereum (once it goes PoS).
They could even do some kind of "diminishing return" model where the first person seeing an answer pays a bit more (say $0.10) and as more people see the q&a they pay less and less until it is practically free.
