A bit more than a year ago in 2014 Microsoft announced that they would be making the .Net Core run time open source and available for Mac and Linux.
Microsoft followed up in November 2015 last year with a partnership with Redhat to support the technology on their servers.
The recent acquisition of Xamarin however indicates that Microsoft is very serious about expanding .Net to as many environments as possible, and this means also supporting developers who do not want to code on Windows.
A job posting by Microsoft indicates that they are working on to “deliver a world class interactive programming experience to thousands of developers like yourself, focusing on scripting and debugging tools so that developers can be super-productive” who are working on Mac and Linux as well. Microsoft is looking to create “rich, language aware tooling enables them to reach their full potential in productivity.”
Presumably the acquisition of Xamarin will help bolster these efforts even further and help Microsoft reach developers and users no matter what platform they use.