As for the effects of below-replacement birth rates over the long term, there is no denying the catastrophic results upon a society. First, the modern welfare state cannot sustain itself without successively larger populations to pay increasing benefits of aging former workers. Second, declining populations require massive immigration to supply new workers as older natives retire -- artificial replacements for the never-born. Even the continuation of economic activity becomes dependent upon fresh supplies of new immigrants. When these immigrants come from alien cultures and refuse to assimilate with their vanishing hosts, inevitable upheavals lie ahead.
Once a demographic tipping point is reached -- when a population ages without replacement -- the math begins to work very swiftly. Any corrective reversal will take decades -- decades during which stronger and growing societies can sieze economic and military advantage. There can be no stability in the face of continuous population decline.
Good catch, but she does make one good point. Liberals are going to use the issue to ask for more and more Government.