I doubt that. There are both men and women who prefer small.

What might happen, is that whatever cultural ideal becomes contemporary, is also what most people will opt for, but that won't mean people on the fringes of the bell curve stop existing.

I find it more likely that if big breasts become "easy" to get, the ideal will simply shift to something else, as the rarity is part of the appeal.

If a trait becomes common, at least some portion of people lose interest.

re: gene editing

Ummm what kind of deranged psycho would sit in a doctors office and specify:"I want my daughter to have huge tits!"

Speak for yourself

turns around with massive cans

I don't think that that many women want bigger boobs. I have more friends who dislike having big boobs vs small boobs.

We already have drugs that increase breast size, they just have the primary purpose/drawback of inducing lactation.