This seems by far the most promising proposal because it (theoretically) means the readers actually become editors. However, it has the same shortcomings as the error reporting: false information can be missed by the reviewers due to the sheer quantity of feedback. This needs to be addressed by design (powerful validations which need to be aware of property types and meaning, perhaps a sandbox, a way to identify and block repeating offenders)
Also, reading Extension:WikiGrok/Lessons_learned it would seem that there is a lot of traffic needed to update an infobox, for instance (see the comments about the API limitations). How does that work for users which do not have access to Wikipedia Zero?