Would it be possible to have a “community accepted” feature?
Could you add a feature which would permit to tag a question as solved if several users flagged one of the response as the solution? Obviously it would only be available for questions lacking a checked answer and after a certain period of time.
In the unlikely edge case where the user comes back and accept another answer, the answer previously selected by the community would still be tagged but not as prominently as before.
Thresholds would have to be chosen, here's what I would pick: (question) 3 months, (voters) 1000–3000 rep and 4–5 users.