How would Microsoft destroy win32 platform?

It depends. Some Windows 10 pre-install tablet computers now require you to flip a switch to allow installation of Win32 programs. And if your program/installer is not signed by a certificate that Microsoft recognizes, you will get some severe warnings when trying to install. It’s even worse for those who need hardware drivers – without code signing, it’s basically impossible to get normal users to use your things.

Similarly, when downloading, Microsoft (like the other browser vendors) will say “this is not a recognized binary; we recommend you don’t download it, to stay safe!” Currently, only for binaries that really aren’t often downloaded, but they can tighten that up as much as they want. And add requirements for what they allow in the Windows Defender tool suite.

The death blow they can deal is to create the default account as non-admin. At that point, you can’t elevate privileges to install new software. Meanwhile, software from the Store installs fine without elevation. Game over, for 95% of users! Meanwhile, they can still say “but users who want to can create an admin account.”