Are you thinking this augurs more interoperability features in C?

Why should it?

COM and WinRT (basically COM Next) are the way to do cross language Interoperability in Windows since VB 5 replaced VBX with OCX, it was a key feature in .NET Framework design, and revamped on Windows 8, when WinRT was introduced as the original design for .NET (Ext-VOS).

https://arstechnica.com/features/2012/10/windows-8-and-winrt...

See windows-rs crate.