"Replacing Chrome" is a stretch; the article also notes "The Chrome browser and operating systems aren’t disappearing — PC makers that produce Chromebooks will still be able to use Chrome. But they will now have the choice of Android." Also see Google is 'very committed' to Chrome OS after Android merger reports (The Verge).
"Google loves scale. It shutters products with user numbers that many companies would kill for (remember Reader?) because they don’t reach the billion-plus of its flagships. Chrome primarily lives on Chromebook devices. Gartner estimates Google will ship 7.9 million devices this year. Android, Google recently announced, crossed 1.4 billion users. Very different scale.Google Plans to Introduce Android Laptops, Replacing Chrome as OS | Re/code
Despite some traction, Chromebooks are still a tiny slice of the market, and Google has faced difficulty corralling developers to build apps for it. It hasn’t had the same problem with Android."