From now on, if any application, which has been installed using Google Play, tries to push app updates outside Google Play, it can be removed from Google Play. So, developers be careful.
Here is full sentence from the “Dangerous Products” section of Google Play Developer Program Policies:
“An app downloaded from Google Play may not modify, replace or update its own APK binary code using any method other than Google Play’s update mechanism.”
You can find the full document of Google Play policies here.
