That's different from "killing" the product / technology, which is what Google does.
I can write something with Microsoft tech and expect it with reasonable likelihood to work in 10 years (even their service-based stuff), but can't say the same about anything from Google.
That alone stops me/my org buying stuff from Google.
And even if C++/CX and C++/WinRT aren't that great, with worse tooling than MFC and in maintenance mode, you can easilly create an application with them today.
Hardly the same can be told of most Google technologies.