What would change if a woman can predict when her menopause happens?

Read up on menopause. It is something that happens over a looong period of time, “predicting” it is only possible if it is forced by circumstance, as in dramatic medical circumstances.

If a woman new she was going to go through menopause very early (outside of the norm) she might have kids sooner rather than later or freeze eggs or embryos. Otherwise, knowing the exact age she will start the process or completely finish with cycling probably doesn’t matter much. I guess if someone has a really crappy time of it, it might matter for planning very long vacations of a lifetime. Once done not having to worry about a period on vacation is great.