Key point from the article:

> ADB would be unaffected, and any power users who needed to install an app straight away could always connect their Android device to a computer and use ADB commands to manually install - no delay at all.

So in practice this won't be an issue for anyone tech-savvy who uses their Android device with apps outside of the Play Store, as they can simply install through the ADB mechanism via a separate device. It can even be done using WebUSB.

However, the many, many people worldwide who lack such technical knowledge, and are more susceptible to being scammed via malicious app installs because of it, are still protected by this new process Google are introducing.