It may be to China's own advantage to study and then innovate for itself how America created the "melting pot" concept, grafted it into its DNA, because it's easier to keep the civilization-state unified if the Hans embrace the Tibetans, Uyghurs, Mongolians, and 52 other minorities China currently recognize as "Chinese."
On the contrary, China is a 3000 years old "melting pot", and that melting is really biologically in DNA. Many DNA test across Chinese mainland shows that, for example, northern Han is genetically closer to their minority neighbor (than southern Han) such as Tibetan to the west, and Mongols to the north or Manchus around Beijing and Manchuria. While southern Han shows closer link with southern minorities. This is due to the thousand years of migration and intermarriage. Together with the genetic infusion, comes the culture infusion. During the last 3000 years, there have been many nomadic invasion and migration from the northern stepps and central asia, and enormous Han's southern expansion. There have been many northern nomadic people amounted hundreds of thousands who ruled northern China at some points of time but disappeared in the history. No, they are not killed off, they simply fused into the Han identity becoming Han (Chinese in western term).
The Han is not a "pure race", but an ongoing mixing group, it has been embracing other people since its birth, Xiongnu (related to Hun as west knows according to some), Turks, Mongols, Qidan (Khitan), Jurchen (Manchu), Xiabei etc. In a sense, Han is a snowball.
I do not agree with the idea of Han being a homogeneous people held by many westerner and Chinese. The homogeneous concept about people or ethnity is really a mordern western concept from the early 17th century during the nation state building. China was only exposed to it in the late Qing era (1890s up) which was then picked up by the early republicans (such as Sun Zhongshan/Sun Yat-sen) to rally people overthrowing the Qing empror (Manchu).
The negative impact of the introduction in China stopped the naturally "melting" process by emphasizing the ethnic difference of two people and locking each other in their distinct catagories. It turns many economical conflicts into an ethnical matter that only worsen the relationship. There is an ongoing louding voice among Chinese to abolish the ethnity identity in legal and adminstration framework, such as removing the entry of ethnity in the civil registration and personal id card.