I think more than any other phenomena falling TFR will affect the world more profoundly than anything else & this is where momins at least in our part of the world are at a huge advantage.
Do not be surprised if you're a 20 year old today with ambitions of settling in say UK or France where when you turn 75 , you see your entire neighborhood being dominated with the color green .
This is more or less a given. However this is not a given in India at least except in some pockets like Western UP , West Bangladesh, Al Geralam, etc .
Already given the preponderance of Single Child Families ( SCF) in metropolitan areas for Hindus it's a matter of time before DINK becomes the norm tomorrow & SCF becomes the norm in Tier II, Tier III cities.
What this means is our internal civilizational fault lines will have to be confronted within the next 2-3 decades. In any case given the developments in our neighborhood we're headed there.
We don't have the luxury of waiting it out till the last quarter of this century as I previously thought.