The reason the pill will have such an effect in the 21st century is that many advanced societies will depopulate - with very few kids and lots of codgers. The prospects for western Europe and Japan are pretty bleak. Even China is going to have problems in a couple decades because of their one child policy.
The end result will be that non-citizens will be brought in to do the work and support the old folks. Those people will bring new traditions and societal values and could change the ethics and culture of the host society.
The U.S. is moving toward a white European minority (if one considers Hispanics non European - I'm not sure of that), but has been importing and assimilating young immigrants to service the old white folks.
Assimilation may well be the issue of the future. European immigrants tend to end up in non-assimilated ghettos. American immigrants tend to assimilate in a short time frame.