Corporations are going to want the cheapest possible solution, so immigration is far more likely.

Exactly this. When a family could buy a house and raise a whole bunch of kids on one minimum wage income, you had a baby boom. Now wages have stagnated where you can barely make it as a childless couple on two wages, why the hell would you have kids in that environment? They spent 50 years chipping away at any kind of social program that helps people, and now they're complaining that the capitalist eternal growth Ponzi scheme could collapse.

Indeed. I think providing assistance to parents would be the best solution.

Yea no of course they aren't going to do this, they are going to do the most blunt pigheaded way to solve the problem (for the time being)