Guessing what will happen to China in future is a mugs game. The country is unusual for being so large and so continental and having such an irregular history of regime change. Moreover virtually all lists of Chinese dynasties have different dates. This inconsistency is striking before western historians started monitoring China (ie, after around 1644) and isa rather telling comment on the accuracy on China's historical record keeping. (This useful source has different dates to everybody else but has the advantage of containing the Chinese characters of different dynasties.)

Nonetheless there are a few safe insights from China’s past. Foremost of these conclusions is that China is like all other countries: it has dynasties and ruling eras that come and go. No leader lasts for ever. The table below lists the previous thirty or so administrations of China. This is not all that is claimed within the often dubious history of the Middle Kingdom but starts from around 1776 BCE; so, around four thousand years.

The last thirty or so regimes in China's history show not a united country but a disunited and turbulent continent. In fact the first united regime of what is today called China was the Chin era. This lasted for a very brief fifteen years from 221-206 BCE. Since then most dynasties in China have usually lasted under a century. Few make it past a hundred years although there are exceptions to this rule. Longer lived dynasties include the Shang/Yin era that may have lasted 654 years (1776-1122 BCE), the Western Chou may have survived for 352 years (1122-770 BCE) and the Eastern Chou may have survived for 241 years (722-481 BCE). Three dynasties from later periods are also long lived: the Tang lasted 289 years (618-907), the Ming lasted 294 years (1368-1662) and the Qing lasted 268 years (1644-1912). 

Assuming these dynasties and dates are somewhat accurate over the last few dozen rulers China has been united 12 times (35%) and disunited 22 times (65%). Thus for most of the time China has been divided between competing entities. 

Disunited regimes last for 119 years. This is slightly longer (+25%)  compared to 97 years for united regimes.

Given so many changes of administrations in China, regardles of whether the continetnal landmass was united or disunited, last not so long it is fair to say the Communists are lasting quite well. They are already approaching six decades. That makes them longer lived than several past regimes in China though far younger from the longest lived. So t he Communists probably have further to go. As noted most of China's dynasties have come and gone within a handful of decades. Some odd outliers push this average to 275 years. But the average of the last ten dynasties is much less: 97 years. Should this hold into the twenty-first century then the Communists are already past two-thirds of their shelf-life.