Here is my memory of the tasks that lay ahead of us in order to roll out Jest Circus. Feel free to add anything that I'm missing.

• Get all of Jest's own tests passing with JEST_CIRCUS=1 jest-circus feature parity with jest-jasmine #4362
• Run Jest with JEST_CURCUS=1 on a few large code bases. Resolve all issues and add regression tests.
• Add some sort of strict/warn mode where users can opt into warnings/errors if they are using Jasmine APIs not supported buy Circus. (@captbaritone) Add a "errorOnDeprecated" mode that errors when calling deprecated APIs #6339
• Expose jest-jasmine in such a way that it can be used as a custom runner for those that can't yet move to jest-circus. (that's free - testRunner: 'jest-jasmine2)
• Make jest-circus the default runner, with guidance in a blog post/changelog that people can use the jest-jasmine custom runner if they need to.
• Remove the JEST_CIRCUS environment variable and the SkipOnJestCircus helper class.