Wood Mackenzie has cut its global GDP outlook to 2035. China, India and the US sit at the heart of this downgrade. Specifically, China's GDP growth is forecast to slow to 3.9% by 2035 with total output forecast to reach US$15.1 trillion, 17% lower than our H2 2015 forecast. China’s easy wins are over. Policymakers now face hard choices to tackle deep-seated structural challenges. The recent ‘Two sessions’ and '13th Five-Year Plan' suggested continued prioritisation of short-term economic growth over structural reform, which will compromise long-term growth potential. In this Insight we focus on the key reasons for China’s GDP downgrade by addressing the following questions: How much further does China's investment has to slow? What are the key drivers of China's productivity gains? Will two-child policy boost long-term GDP growth? How does the GDP downgrade differ by province/region and what are their key drivers of growth?