I was going to post a seperate thread for this (and maybe I still will), but I really wish iMessage had an “unsend” option. Most other messenger apps these days have it. I’m sure we’ve all sent a message to the wrong person by mistake or simply changed our mind about a message at some point.
Since iMessage can tell if a message has been read, if it hasn’t been it could even disappear entirely so the user never knows it was sent. Otherwise it could simply show an “unsent” bubble in place of the message.