Comment by jongalloway2

I think the big difference is that .NET and Visual Studio will depend on the Roslyn compiler. Rotor was a sample implementation, but nobody at Microsoft (to my knowledge) was shipping an actual product / project that depended on Rotor moving forward. I've talked to leads on the team who are excited about being able to roll out new language features using this new compiler. There's a good, long term business justification for Microsoft to keep working on this after open sourcing it, which I've learned over time is a very good and important thing.