Millions of Galaxy S3 users will be disappointed with this.
However, that is not the main reason. Among the updated devices, the Galaxy Grand only has 1GB of RAM but is still supported. In addition, KitKat is optimized by Google to be able to run well on devices with RAM of 512MB or more.
Other information said, US market Galaxy S3 with RAM of up to 2GB will receive KitKat update 4.4.
Below is a full list of supported devices to update to Android 4.4 KitKat: