China united by hanzi or kanji 汉字
Most east Asian cultures are traditionally connected by hanzi, kanji (Chinese characters). Such traditional cultures often share chopsticks use as well. Chinese characters can be read and understood by people who speak totally different languages.
No more true for China itself, the very identification of Chinese Han culture is based on shared hanzi which connects today's Han people with ancient Han writing like Confucius and can be comprehended by people with different dialect's. Like word gold-金, it does not matter when (200o years ago) and where (2000 miles apart with different pronunciation) 金 is written, it still carries the same meaning. This writing system keep Han people connected as one. But in northern China, gold is pronounced `jin'; in Cantonese, gold is pronounced `gum'. If China replacing hanzi or kanji with sound based alphabet, each province or small regions would have totally different writing with mutually incomprehensible local dialects. The result is that China will become numerous different countries since they will be considered totally different cultures and people. Without hanzi, China itself will fall apart. Han culture would shrink to small area in the north of China.
Sound based writing is vulnerable to constant changes which make today Greeks could not read their ancient writing with ease. Latin also became a dead writing.
Only country outside of China still preserve some hanzi is Japanes kanji. No wonder a Han and a Japanese can communicate with each other by writing kanji. Korea and Vietnam have abandon the hanzi to facilitate literacy rate. But high literacy rate does not automatically translated into higher economical achievement if you compare Vietnam to Japan or China.
Gold is only form of money which has no time and space limitation. Like gold, 汉字 is only form of writing can cross time and space.