"Starting in late 2016, newly-published Chrome apps will only be available to users on Chrome OS."
As someone who has been building a Chrome app this sudden change with a lack of notice has made me very nervous.
But if you want to maintain a presence on ChromeOS, you can keep updating your app indefinitely, but it'll only run on ChromeOS starting sometime in 2018. Or you can redevelop everything for the Google Play Store (ie. the Android store) if your ChromeOS customers are on new-enough ChromeOS devices to get access to the Android store, leaving old ChromeOS devices stuck on the old Chrome App version. Or you can redevelop everything as an entirely HTML5 single-page-app with all the lovely ever-evolving, impossible-to-keep-up-with features or lack thereof [1] of the web platform. Or you can redevelop everything and go full-native on every single OS. Or you can put all your JS into Electron and hope people don't mind a 60+ MB download. The choice of awful choices is yours.
As far as I can tell, there will be no way to programmatically transition users and their IAP outside of your chromeapp. Meaning, we will have to figure out a way to get users to register their purchases to a database.
It will be very disappointing if Google doesn't help make this migration easy.
Currently, it's up to you to create hooks upon successful payment to ask for information (which is extremely weird to the users because they're under the impression that they paid you directly and already possess that information).
Every In-App-Purchase (or app purchase) is not linked between platforms. It sort of makes sense that any IAP you buy in iOS will not (automatically) make it over to Android, but it makes less sense between Android and Chrome (considering it's the same Google user).