Sure they could add rules to the "Google Play agreement for Fuchsia" but they are already in hot water because of the current Play Store contracts.
Creating an "open platform" encourages device makers to polish it only for their needs but not upstream features and fixes to competitors (OS fragmentation) and let multiple, insecure versions run forever that rarely get updated (legacy fragmentation). Plus, Linux security is usually an oxymoron which Fuchsia may address. If Google wants their platform to survive, they're going to have to require approval for apps and devices, and stipulate things like UX usability and mandatory OS patches.
PS: There are thousands of servers run by handset manufacturers and telcos that are required for some features of mobile devices to work at all. For example, Motorola Mobility smartphones' depended on their own servers for many social media features to work. These backend-heavy designs are supremely easy to brick, disconnect and invade privacy of users, en masse, for profit and for government spying.
Sounds like a great conspiracy theory. Looking forward to the evidence to back up this link bait article.
Most of the comments here miss the point of the article. The article author is saying that Google will replace the Linux component of Android with something proprietary. Then Google will have total control, and will be able to prevent Android clones.
Already, Android apps make such heavy use of Google proprietary code that open source Android systems such as Cyanogen and FDroid have mostly given up.