Unfortunately, too little too late. That ship has sailed.
So many people have switched to platform-independent messengers like WhatsApp. These messengers happen to be also superior to iMessage when it comes to features and reliability.
This. I hate WhatsApp (because of FB) but it has become the de facto platform where I live — school groups, meet ups, business discussions all take place on WhatsApp. They were way ahead of the game on features like group moderation, deleting messages, quoted replies, etc. And now they own the market.