The thing that I want to know is... why does it really matter? Women have been aging and getting saggy boobs since the dawn of human evolution... bras and corsets are not terribly old in terms of human history. Do we as women feel pressure to have "perky boobs" more now than ever?--and if so, how valid is that pressure, if it's not coming from ourselves? (e.g. coming from society, marketing, porn, men's expectations, etc.)
And if it is coming from yourself, then I see that as being different--each to her own, and be proud of it!
That's a personal standard, and I can't question that. But I have a strong opinion that all of our bodies are beautiful as they are, as long as we keep ourselves healthy and not at one extreme or the other--and the more we accept them as they are--gravity and all--the better it is for women everywhere. I don't like having to conform to ideals of a female body, I guess... especially ones where "youth" is everything.