From 2U's press release [https://2u.com/latest/industry-redefining-combination/] it's clear that they benefit significantly from associating themselves with the MIT, Harvard, and EdX brands. At $800M, I assume they have a well-planned monetization strategy for EdX.

My personal experience with EdX over the years is mixed. I audited a few EdX courses (CS50, Linear Algebra) and generally enjoyed the quality and pace of the courses, but was never compelled to purchase a verified certificate since these were more for leisure. I recall hitting up against the paywall and losing access to the exams. Although, I understand the need to monetize, it was a bit demoralizing.

Overall, I feel EdX helped define massively open online education and I hope they continue to support this mission in the future.