Google has confirmed a major change in the way Google Play Store distributes app updates. Now the pre-installed apps will get updates even if you have not signed in with a Google account.
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Google has notified to certain app developers, who have apps preloaded on the phone, about the changes. Google says that all the apps affected by the changes should be updated to reflect the new policy change.
This will work only for devices that shipped with Android API version 21 or later. It means pre-installed apps on devices running on Android Jellybean or higher will not require Google account for updates.
You still need to sign in for installing new apps from the Play Store. This change affects pre-installed apps only. For example, when you set up a new device without signing in a Google account and open the YouTube app, it asks to update the app. If you want to update the app, you need to add a Google account, but soon you will be able to update apps without singining into any Google Account.