So in a sense, that's inevitable, isn't it?

The alternative would be to ensure that birth rates are such that the population distribution across ages is always vaguely balanced, but due to the changing socioeconomic conditions, I doubt that's viable. So all that can be done for the most part is just to have social safety nets and support for the older people in the forms of affordable housing, discounts, pensions and other such systems.

Here in Latvia a certain part of each salary is put towards our retirement funds, be it through a privately managed set of funds (typically through one of the banks) or otherwise. The sizes of pensions and living expenses are still a hotly debated topic, given that those still aren't always sufficient for a comfortable lifestyle, but the idea of accumulating enough money for when you age seems like a sane approach to the problem at hand.

Money in a retirement fund is just an IOU. The actual labour of your retirement - the bartender serving you drinks, the doctor performing surgery, the carer taking you to the toilet - is done by young people. If there's not enough of them around, the money will very quickly inflate towards worthlessness.

While some current projections do predict a steep decline in population growth - it's still gonna take roughly a hundred years, just to reach zero growth. Which means we are looking at another 100 years of population actually still growing.

If the trend continues unchanged, and population growth goes negative, it would take another 100 years just to return to exactly the same population numbers that we do have today.

If the growth then grew even more negative for another 100 years, that's when you'd be able to talk about an population implosion - 300 years down the line. So no, I don't think there will be any implosion within our lives.

The problems you describe though - that's not implosion, but population aging and the economic problems that causes down the line. Those issues have been around in some countries for multiple decades already - and yes they are going to get worse. Still, growing population numbers to levels beyond what this planet can sustain just to keep the economy afloat does not seem like a well thought-through plan to me.

We will have to achieve zero population growth - and if the world economy can't take that... we really need to radically change the economy, not increase population growth again.

In the past, some people argued for a much smaller world population (however they imagine we could possibly get there), but now that it might happen, we realise our economies run on young people.

And yet we don't pay young people enough and we don't give them the opportunity to start families. Much of this is definitely also a policy problem: make sure young people can buy a house and start a family, can afford to raise kids, have time off with their family, etc.

We can afford a contraction.

You need a certain tax base to keep services funded. Then at some point on the curve, you start running out of service workers for the care industry.

I think automation will help to a degree but healthcare services is right at that sweet spot of both physically intricate and nonroutine that is so hard to automate.

It's not that bleak, only until humans are extinct.

I don't know who are "we" and if they can afford it. I suspect most don't know either and think they "afford" part is not their part or imagine it's having one less latte/month in exchange for less traffic.

Humanity can afford it, you might not

I don't think it makes much of a difference in practice for this scenario if retirement is funded by savings/investments of the elderly or through taxes and other transfers from the working population. As much of the population is retired the value of the investments will go down as now now people are selling than buying new investment. It would become a indirect transfer.

Humanity can afford it, you might not. But policy should probably be set to benefit humanity.

There’s simply fewer high school graduates available, so enrollment counts will go down and universities will have to fight harder or lower admission requirements to keep the same number of students year over year.

It could also be that young people today simply don’t want to pay the high cost of college, and honestly I get that. But even cheaper or budget colleges are seeing enrollment dips.

The Amish.

I'm not quite joking. They're some of the best farmers on the planet and they have huge families. I suspect, if you do the math, they smoothly replace the rest of us as we "grey out" so to speak. ;)