Some blog posts (in chronological order) documenting the progress of this project:
https://devblogs.microsoft.com/typescript/typescript-native-port/
https://devblogs.microsoft.com/typescript/announcing-typescript-native-previews/
https://devblogs.microsoft.com/typescript/announcing-typescript-5-9/#what%E2%80%99s-next
The codename of the existing compiler written in Typescript is Strada, and the codename of the new one written in go is Corsa.
The TypeScript team has consistently said that Typescript 7.0 will be the first stable release of Corsa. They have also said that version 6.0 will be the next release, and will contain breaking changes designed to align with the behavior of Corsa.
Update 2025-12-03 (PST) (AI summary of creator comment): Microsoft has announced there will not be a TypeScript 6.0 release, meaning TypeScript 7 (Corsa) will be released sooner than previously expected.
See: https://devblogs.microsoft.com/typescript/progress-on-typescript-7-december-2025/
While 6.0 has not been released yet, Microsoft has just announced that there will not be a Typescript 6.0, meaninng that the release of Typescript 7 (Corsa) will be sooner than it would have been otherwise:
https://devblogs.microsoft.com/typescript/progress-on-typescript-7-december-2025/