Udemy was able to get teachers to use their platform by sharing most of the revenue with them, but once they had a large platform, they cut the revenue sharing

Udemy was able to get teachers to use their platform by sharing most of the revenue with them, but once they had a large platform, they cut the revenue sharing dramatically. It's very hard for competitors to take on a dominant platform,even Craigslist still manages to dominate many areas. However instructors can list their courses on both Udemy and on other sites, so this could be something a competitor could try to build off. Perhaps competitors can chip away at specific niches of Udemy, just as happened to Craigslist. For example, one site could focus on business, while another covered web design. Personally, I would be interested in building up a platform around programming courses. This site could offer a number of improvement over Udemy, such as coding challenges and a better format for video. It could also instructors a guaranteed lifetime revenue share above a certain point (say 75%).