What exactly is changing?
- Icon assets will remain the same size (512 x 512), but transparent backgrounds will no longer be allowed.
- Google Play on Android and Chrome OS will dynamically apply rounded corners and drop shadows to icons. The corner radius will be 20% of the icon size, to ensure consistency at different sizes.
- There will be no changes to Google Play on other form factors (TV, Wear, Auto).
- Note this does not affect your APK launcher icons for Android.
More info here and here