Maybe I'm buying too much into this, or missreading something. From the looks of it, they want more programs to be available in MS Store. This is essentially MS version of snap/flatpak app container. Plus, it's open-source.“The MSIX Packaging SDK project is an effort to enable developers on a variety of platforms to pack and unpack packages for the purposes of distribution from either the Microsoft Store, or their own content distribution networks,” Microsoft explains.
What I'm not sure is if this could be used to bring existing win32 and other programs previously only available for Windows to Linux and Mac (even Android maybe).
As someone said, Windows is becoming more and more like Linux and ironically may be what some people wanted Linux to be on the Desktop.
Again, maybe I'm jumping to conclusions. It's too soon to tell.