Rome was not democratic, but it did achieve greatness and dominance. China will not achieve greatness if she cannot eliminate nepotism and corruption. Two weaknesses in her society that lead to the downfall of all her dynasties with the exception of Chin and Yuan and Communist Rule is a dynasty. China is not ready for democracy because 90 percent of her people are rural poor and only 10 percent are middle class or better and they live in the coastal cities. If China became democratic, she will go the way of Venezeula because the pent up resentment of the well to do by the majority rural poor will lead her to “mob” socialism. China’s expansion will be limited by energy and a large elderly population that will be a burden on the smaller younger population (due to elderly longevity and the one child policy). All the Asian Tigers (except Japan) had authoritarian governments that presided over economic expansion and modernization, and once a large middle class is established, the authoritarian government either relinquished to democracy or were driven out. Democracy without a large middle class will lead to Venezeuala mob rule.
Over the course of its 1000+ years it was just about everything one time or another.