I'm not sure if it is possible for the entirety of China - that is, all 1.4 billion Han and non-Han Chinese - to have living standards on par with Japan by 2020, at least with a 19th or 20th century PoD. It would require a completely different process than what led Japan to its current position, as the entirety of Japan's population lives less than 120 km from the ocean and Japan's population was much, much smaller, more homogeneous, and more educated on average.
It's certainly possible for China's coastal regions to develop on the same lines as South Korea, Japan, and Taiwan, but one has to remember that one segment of a population becoming massively wealthy while a much larger segment remains comparatively poor is a recipe for disaster in any country. Mao was basically able to solidify his rule for life by pillaging the wealth of the coastal elites in the name of the poor inland peasantry. Most regimes would prefer to rule over 1 billion peasants than 900 million peasants and 100 million wealthy urbanites.
Improving standards of living across the entirety of China has been the country's biggest challenge since Deng Xiaoping's reforms. While Chinese in the coastal cities have incomes nearing Western levels, most Chinese in the interior have incomes on par with Sub-Saharan Africa. China's proposed solution has been the Belt and Road Initiative, a massive infrastructure program that has been extraordinarily expensive and less than successful up to now.
For all intents and purposes, the CCP has the right idea - having good infrastructure is critical to improving standards of living. The problem is that it's just not cost effective. The United States has the benefit of a West Coast, less rugged terrain, and a vast network of waterways, not to mention a much smaller population, so throughput was never a huge concern.
In conclusion - if China had not gone down the Communist route, it's eastern populations might have ended up as wealthy as Japan, however this would have come at the cost of political stability, which is much more important to most historic Chinese governments than standards of living.