A similar thing will very soon happen on MacOS. The next version, MaoOS Catalina will also completely remove 32-bit support which means Steam and most of the games on Mac will no longer work once you upgrade to Catalina
The Index does not make it illegal to possess or play the game. It just regulates that a game cannot be sold to minors. Also, the game cannot be advertised or displayed openly.
I wonder what is the purpose of the DVD delivered with this expansion. Its contents are identical to the original Diablo III DVD. All new content has already been delivered by installing the patch.
What do you mean "joins Steam"? I've had this game for ages on Steam, and I'm sure GFWL had already been removed earlier. I checked for that only last week, and there was no trace of it anymore.