When abortion rights become even more mainstream and accepted then they are now, probably in the 2020s and at the latest, 2030s.
I'm not sure that will happen. According to several polls, younger voters have approximately the same views on abortion as the older generation. Some polls even suggest that younger voters are slightly more pro-life. Thus, I don't see opinions on abortion changing anytime soon, especially considering that the younger generation grew up in a much more liberal environment than the older generation.
None of that matters. Over time, more socially liberal generations emerge, and old "conservative" beliefs are struck down. The cycle, as always, will repeat itself.
You say this though all trends show the opposite? I am curious as to how you come to the conclusion that pro-choice views are increasing.