It's happening already, I'd just not create incentive programs to boost birthrates. I don't like to take a very heavy handed way to "control" society, think it's better to just let some things happen the way they happen, because if I'm wrong at least I didn't go full on. But the most developed / educated countries are already going down fast except for immigration. Once the countries immigrants come from rise to the same economic levels, I would predict their birth rates would also go down.
To your tangential point: I think technological development will allow less and less people needed on the supply chain to sustain the same quality of life for society. I think this is clear from history and it only goes in one direction.
I'm aware there's people that defend more extreme views like boosting abortions or other dystopian measures. I don't believe in any of those, I think everyone should have the right to reproduce if they feel like it, I'd just rather it be an informed decision, but I wouldn't add any control measures for fear of abusive mis-use by the government later on.