> MS will have graduated to the next level of maturity when it open sources something that is strategic to the ecosystem and the ecosystem as a whole benefits
Dotnet Core is cross-platform and fits that bill.
It introduced a huge segment of Windows-only devs to Linux.
Yes, that furthers Microsoft's goals too, as Linux is very important in the cloud, and therefore Azure. But regardless, the move has also benefited many, many developers, and the Linux ecosystem.