Microsoft’s next version of the .Net software development framework will be .Net 5, and it will be the only branch of .Net going forward. There will be no more separate releases of .Net Framework and .Net Core.
Due in November 2020, .Net 5 will follow the release of open source .Net Core 3.0, which is currently in a beta release stage and due to be generally available in September 2019. Like .Net Core, .Net 5 will work on Windows, Linux, MacOS, iOS, Android, tvOS, watchOS, WebAssembly, and more.