Aww - yes I think it will also.I think most have missed the question the OP was making, obivisouly the 2017 iphone plus will have at least 3gb of ram. I believe he was asking if the 4.7 iphone will have it, I think it will.
IOS 11 only 64-bit finally!!! However in the future IOS updates will require more RAM .If it has 3gb, it's because it was needed for the extra software stuff behind the curtains. The stuff we don't see.
If they have 3gb now, it will have it in the next ones too. If they need more, they eventually get more. We don't know anything about the 8 yet, maybe the redesign and ios11 only needs 1gb because they pull some magic. I think it's a bit too early