What will become of oil- and gas-producing countries?

The energy transition is going to require a gradual phase-out of oil and, later, natural gas production. But a number of countries receive a significant share of their income from the sale of oil and natural gas and have not diversified their economies much. There is cause for great concern for countries that have not diversified sufficiently into other industries, especially if they have a large population. This is the case of Iran, Angola, Venezuela, Russia, Malaysia, Saudi Arabia and Algeria.