I think we need to accept that there will be a top-heavy population for the foreseeable future and plan for it.
It's probably too late now to avoid the scenerio of large numbers of elderly people/pensioners with increased care needs, and insufficient workers/tax receipts to meet those need.
So we need an honest and open conversation about what people can realistically expect from the state in terms of care/healthcare/pension benefits given the demographic challenges we will be facing. The truth is that the state may not be able to guarantee a comfortable and dignified end to life for everyone and all options need to be considered, including uncomfortable ones like assisted dying.
We're probably in this situation already, when you look at the inadequate social care provided for many people, but haven't admitted it to ourselves yet.
The problem is - yes, there are some women who want 3/4/5 children but there are a much larger number who only want 1/2. And a growing number who want none at all. And this is unlikely to change so the population will probably keep on shrinking.
In the end, I suspect decent care will become astronomically expensive (if it isn't already) and available only to a privileged few. Most people will become dependent on family. For those who don't have children or whose families are unwilling to help, the future will be very bleak indeed unless they've amassed considerable financial security.