Evaluate the consequences of changing population trends for both MEDCs and LEDCs

In the 1950s-60s, the « population explosion » caused major concern about mas starvation in the Global South, leading to the Green Revolution.
Nowadays, trends have been reversed : in most countries, population growth is falling and people are ageing, causing a « papy boom .» According to the Demographic Transition (DT) model, this should indicate that countries are more and more developed as they are advancing in their DT. However, although all countries follow the same patterns of population change, it does not necessarily mean that they are improving in terms of development. What are the real consequences of these shifhting populaition trends?
They can be divided in three different categories of consequences : effects of ageing population in both North and South, consequences of decline in population in MEDCs, and influence of falling population growth in LEDCs.

World population aged over 60 years is increasing, in absolute as well as relative numbers. [This increase is a result of improvements in health care technology and availability coupled with a reduction in fertility rate due to widespreading use of contraception.] Emblem of this ageing population is Western Europe, where countries like Italy count around 20% of their population over 60. [However, it also concerns other countries around the world : for instance, average proportion of elderly dependents in Africa is expected to triple between 2000 & 2050, reaching 25% of total population.] (these parts do not really answer the question)
The first impact of an ageing population is the increasing dependency ratio (total number of young or elderly dependents per person aged 15 to 55). This means that social and economic pressure is put on workers, with higher taxes and an increased necessity of having a job. A high concentration of elderly people in MEDCs can provide jobs in tertiary sector businesses, such as banks,