So what are developers of existing paid Chrome packaged apps suppose to do for existing users? "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.
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.