Well, I still own a 4S, so I don't even have to worry about it - for now - but this week I learned that iOS10 lost the ability to "Send as SMS" by long-pressing on the message. No more. This can now be used to add emojis to the message after it was sent. WTF? And if the other person doesn't have iOS 10, one get's a second message with "X has added an exclamation mark to the message" or the likes. Sometimes, you really need to be sure it's sent as SMS right now (because you know the recipient is e.g. in a foreign country and has switched off data). Until iOS9, this worked very nicely... But maybe I'm just too old to appreciate all the fancy iMessages crap they have come up with instead.... I use SMS to send meaningful (or downright important) text-messages to relatives, friends, co-workers (and sometimes even my boss).