What will happen to a population made up mostly of individuals that are past reproductive age?

A population primarily composed of individuals past reproductive age will likely experience a decline in numbers over time. With fewer individuals capable of reproduction, the Birth Rate will decrease, potentially leading to an aging population. This demographic shift can strain resources and social systems, as there may be a higher dependency ratio with more elderly relying on a smaller, younger workforce. Ultimately, the population may face challenges in sustainability and economic vitality.