The latest forecast by Statistics Korea puts the population in 2072 at 36.2 million, a 30% decline from the current 51.7 million, even though the fertility rate may recover a bit to 0.68 in 2026. The population is expected to fall every year starting in 2025.
It seems for the past few years, it keeps going lower than predicted, and thus the predications keep going down. I wouldn’t be surpised if it instead bottomed out at 0.51 in say 2030