Yes, but there's a balance that should be struck if we want to avoid widespread human suffering.
South Korea is the most obvious cautionary tale.
In 2000, their average citizen was aged 32.
Today, it is 46
By 2060, it is projected to be above 60.
South Korea’s median age has jumped from ~32 (2000), to ~46 today and is projected to be 61-64 by 2060.
Within the space of a lifetime, the country's overall population will have more than halved, and the remaining population being comprised mainly of people of traditional retirement age, and only a very small portion being children.
Obviously, that has profoundly impacted things like pensions and even the concept of retirement, and it's worsening at an increasing rapid pace. Its not just an economic crisis either, but a cultural one.
The UK's currently trajectory is one of meaningful aging, but at a more gradual rate. It's still a huge challenge that will ultimately need to see society redesigned, but sudden "collapse" isn't a real risk in current trends. We do get much closer to that, though, if we were to suddenly introduce something like net zero immigration - as could be on the cards.
When you're in a plane, your ultimate end destination is the ground. Ideally, that's with a slow descent and graceful landing, not a vertical nosedive.