Global demand for OPEC’s crude will be lower in 2020 than next year as supply from rivals proves more resilient than expected, potentially fuelling a debate on the merits of its strategy to let prices fall to hurt other producers. The Organization of the Petroleum Exporting Countries, which a year ago refused to cut supply to retain market share against higher-cost rivals, in its 2015 World Oil Outlook raised its global supply forecasts for tight oil, which includes shale, despite a collapse in prices.