TeamCity in particular is loved by many enterprise shops, as well as IntelliJ and Resharper. None of those (even IntelliJ) are particularly threatened by VSCode.
Iunno. I'm finding that VSCode is rapidly approaching parity with IntelliJ in terms of features that I actually use, while at the same time being quite noticeably faster and less buggy.
No, but Visual Studio (not Code) is rapidly integrating R# features into VS. Many people are disabling R# because it slows down VS so badly and Microsoft has been closing the gap (see recent 15.8 release with EditorConfig features).