I look forward to being able to use this all in Unity3D in 7 years.
http://blogs.unity3d.com/2014/05/20/the-future-of-scripting-...
so updates in Mono are irrelevant to Unity.
> we will also be upgrading to recent versions of the Mono C# compiler, base class libraries, and runtime for use in the editor
> We will continue to use the Mono C# compiler (and perhaps later, Roslyn). We will continue to use the Mono class libraries. All currently supported features and 3rd party libraries which work with Mono AOT should continue to work with IL2CPP. We are only seeking to provide a replacement for the Mono VM and AOT compiler, and will keep on leveraging the wonderful Mono Project.
Also, yes, this is a replacement for the VM and AOT, but the libraries in Mono are still very useful. Many of them are currently being replaced by Microsoft code as well, though, so it looks like .NET, Mono and il2cpp will share lots of code that way. Just not the VMs.
I don't know man. Mono moved away from Boehm GC to a real gc (SGen) because it never really worked for them bespite feeding it a lot of metadata. Others before them have found out that tanspiling to C/C++ isn't really that great (some of the more recent ones where HipHop PHP).