The y chromosome is a very deleterious, unstable chromosome and is heading to disappearance. Even within the same lifetime, men start losing their Y chromosome in old age and that problem only gets worse with each generation.

Many might say this would mean the extinction of humanity, but the fact of the matter is, people with y chromosomes will just not be needed for the survival of our species, especially with the development of in vitro gametogenesis where gametes, including sperm, can be produced from a person(of any gender) using a different cell, like a skin cell. This process is very near to the horizon and will probably happen for sure within my lifetime, maybe within a decade or two even. So, with that technology, humanity would be able to survive as a single sex species.

Now, I have an interesting hypothesis. Generally children are better raised with more than one parent. When humanity becomes all-female, this would mean same-gender attraction needs to be more prevalent. I'm sure most people are aware here that the queer population is increasing every generation; primarily because more women are identifying as some sort of sapphic as each generation passes. Some suggest this is because there is greater queer acceptance. I think that is part of it, but it's interesting this is primarily impacting women. Perhaps, instead, evolution is getting our species ready to be an all-female species, and as such, more and more women are getting attracted to women with each passing generation to meet that demand.