Earlier quoted context omitted.
And by what mechanism can you prevent google from disabling adb? Or implementing a situation like iOS where sideloaded dev apps only last for a week and are signed with your personal developer key tied to your credit card? There's nothing to stop them, and absolutely no reason to think they won't take away adb sideloading in the near future.
Google have full control to do this on their Pixel devices by rolling out new firmware with further restrictions - though there is no evidence they plan to do so. However other vendors that build upon AOSP, such as Samsung, can make their own decisions on this.
Pure AOSP devices are only some chinese knockoffs without play store. If your device needs play store/device integrity verification, there are lots are requirements by goog that needs to be met. Goog can add new requirement to disable installing unverified apps from adb.