What if China's stimulus and reform measures work? They could boost annual gross domestic product by US$5.2 trillion by the end of the decade. They could also help turbo-charge annual growth in the world's four largest economies by an additional US$10 trillion and the rest of the world by an extra US$8 trillion. While a recent flurry of underwhelming data from the world's second-largest economy has focused analysts' minds on downside risk, China's fiscal and structural reform programme could yet yield surprising dividends. Mapping growth trajectories for China, India, Japan and the United States, analysts at Bank of New York Mellon are working on just that assumption. If ambitious reform agendas for the three Asian nations succeed and a durable recovery takes hold in the US, the bank said in a report, they would combine to drive consensus-beating growth rates for the four economies. "If these four economies were to fire on all cylinders at the same time, it would lift growth and trade in the rest of the world, reverse the slide in commodity prices, and underpin a further rally in global share prices," bank investment strategist Simon Cox wrote. Oil would rise above US$100 a barrel and major stock markets would hit record highs. It is an optimistic forecast, and not without caveats. With China's first-quarter economic growth the slowest in six years, many observers are more concerned about how it will manage a debt mountain that has soared from about 150 per cent of GDP in 2008 to 236 per cent by the middle of last year. Aggregate manufacturing data for Asia was below average last month and underperformed globally. New factory orders contracted and were a full standard deviation below normal, with Indonesia, India and China experiencing the largest slowdowns, according to BNP Paribas. "Without further stimulus, regional growth is set to dip further," BNP Paribas analyst Mole Hau wrote in a report. "While recent moves in China have started to loosen financial conditions, the regional easing cycle has much further to run." For BNY Mellon's roadmap to work, each economy would need to overcome deeply entrenched opposition to reform. In China's case, goals include productive capital allocation, freeing up untapped domestic demand, and restructuring of state-owned enterprises. China would also need to average 7 per cent annual compound growth between last year and 2020, Cox wrote. The International Monetary Fund predicts growth of just 6.2 per cent over the same time frame. Japanese GDP needed to grow at 2 per cent a year, almost double the IMF's top-end estimates, and India must outperform IMF estimates by about 30 per cent, Cox said. In short, while the IMF sees growth rates steadily dropping across the board in the latter part of the decade, Cox's team says they can be maintained at close to current levels. "One of the main assumptions … is a bigger-than-expected output gap in these four economies," Cox wrote. "This greater untapped potential means that economic activity can increase without spurring increases in price pressures. Thus all four central banks … would have more scope to keep rates lower for longer than would otherwise be the case." The impact that even a slight increase in one major economy's productivity can have is impressive. In a recent review of monthly trading patterns between 2000 and 2014, HSBC analysts estimated a hypothetical 1 per cent rise in China's industrial output would boost global exports from selected nations by up to 3.5 per cent. Thailand's exports would have risen 2.75 per cent and the Philippines' by 1.5 per cent between mid-2006 and last year, while exports from commodity-rich Australia would have risen 3.5 per cent. From 2006 onwards, the hypothetical increase in China's output had a larger knock-on effect on regional economies than an identical increase in the US, HSBC found. "What is clear from this exercise is that China is in the driver's seat of Asia's trade, and its influence in the immediate region is only growing, in spite of softer overall growth," it said. Four of the world's major economies growing rapidly in tandem feeding off each other's domestic demand is not something Asia is used to seeing. Even if achieved, the next challenge will be how to balance such a rise in prosperity with the national confidence and assertiveness that comes with it.