Define collapse. The world population is on track to start declining starting in the next few decades. However with 8-9 billion humans how large a loss would you require before you call it a collapse is a debatable question.
Increase in global population will continue for a few decades, but there are more old people than young people and it seems unlikely that we will get to a phase where births are high enough to counteract coming the death by old age in the near future.
I believe this is a good thing even if it will cause many issues. Humanity will have to live on earth for a long time and infinite growth is not sustainable. So at some point the population has to fluctuate. We will have to accept this reality.
Increase in global population will continue for a few decades, but there are more old people than young people and it seems unlikely that we will get to a phase where births are high enough to counteract coming the death by old age in the near future.