I would start with what I expect students to know. They should be able to write very well, have a basic understanding of economics and public policy, and a decent working knowledge of statistical reasoning. I would give a degree to students who demonstrated “B-grade” competence in all of these areas; what now goes for passing C-minus work wouldn’t cut it.
Most important, the people who write and grade the students’ tests would not be their instructors. So students would have to acquire a genuine general knowledge base, not just memorize what is supposed to be on the exam.
Next, each student would have the equivalent of a GitHub certification page. If you learned three programming languages, for example, or won a prize in a science fair, that would go on your page as a credential. But it would not count as a credit toward graduation. Some students could finish their degrees in a year or two even if their pages were not adorned with many accomplishments, while others might fill their pages but get no degree.