Battery life is subjective to each individual user. You think battery life on your phone is a little worse since the update, I think it's way better on mine.
If the updates do come, it will probably be some time until we see it. Samsung and the phone carriers aren't exactly quick at releasing updates like this. Think about how long it took Samsung and the phone carriers to release Nougat to the S7 series.
Us Verizon users just got the update last week.
And there are carriers out there that still don't have the upgrade yet.
Do I think at&t will receive 7.1.1? Probably. But by the time you see it, there will probably already be a newer 7.x.x out there.