Unsustainable (human) populations should shrink, which is alright and can't happen fast enough. A pragmatic and realist approach to demographic management, long overdue by today, I think, was last workable on a large scale in China (1-Child-Policy) and is never going to be effectively implemented again unless a major collapse happens. Ideally, that collapse would be local to areas where pressure on resources is especially high and the cost to civilization is relatively low, like in Africa, so that humanity overall can develop further.