Your feelings couldn't be more wrong on this. Making .NET cross-platform is one of their major initiatives towards creating a more open and future-proof Microsoft and part of the foundation for the next generation of their ecosystem. It's the very reason why Core was split off of .NET. They are betting the barn on this, its not some flimsy side project.

http://blogs.msdn.com/b/dotnet/archive/2014/11/12/net-core-i...

Well coreclr at least has 778 forks on github currently, so it will be a bit harder to pull the plug on hopefully. It's also mit licensed and has a patent promise. IANAL but it looks pretty safe, especially with the mono project picking up the code and integrating it (in theory).

Not just in theory; http://www.mono-project.com/docs/about-mono/releases/4.0.0/

It's actually happening - https://trello.com/b/vRPTMfdz/net-framework-integration-into...

A community is rapidly building around CoreCLR, and there are several companies that have a huge interest in running .Net languages on platforms other than windows (Xamarin, and Unity come to mind).