I think the first scenario would still be a major breakthrough; requiring graduate students to write their literature papers for Wikipedia is a whole different beast from (a few idealistic) graduate students writing on top of their other duties.
Wikipedia is written for the layman, a graduate student's papers are written for the expert. Writing for Wikipedia requires different skills than the ones graduate students are being tested on with their papers, and the skills currently being tested are required, so writing for Wikipedia would have to be in addition to, it can't be instead of, academic papers.