Through personal research and encounters, I have to completely disagree with this statement. Let's not forget that the major national identity that's constructed by the PRC is Zhonghua minzu, not Hanzu or the other minorities. This construct has real affects on the psychology of the common masses.
Just because minzu identities exist on ID doesn't mean people view it the way that it was originally designed in the western sense of the word (and the government doesn't want it to be interpreted that way, and they are successful at it). Everyone knows there are ethnic minorities, but the term commonly understood by the Chinese populace is very different from the American idea of race or nation. The fact of the matter is, the average person in China (Han or minority, the major exceptions being less Sinisized groups like Uighurs and Tibetans, but even here, I've lived among them long enough to see many also follows the standard Chinese view) do not think ethnic minorities are different races and most even think that ethnic minority languages are another variety of Chinese just like Chinese dialects. The idea that most Han people think they are a race separate from the other minorities is an intellectual delusion; most Han don't think like that at all. I've done a survey particularly on the subject and asked minorities (including Manchus, Hui, Zhuang, Bai, and even some Mongols) what race they are, the first thing most of them answer is not the identity on their ID, it is Chinese. Chinese, not Han, is the national and yes, even racial identity. That is the popular view. It is Han minzu which is the bigger political fiction in today's reality, not Zhonghua minzu. The idea that ethnic minorities are not racially Chinese are restricted to a selected few intellectuals.
But they would also include peoples like the Koreans and the Japanese in this "yellow" race, while fully recognizing the fundamental ethnic and cultural differences between them. To this end, whether the Chinese consider themselves racially "Chinese" or "yellow" is immaterial, since they obviously have a different way of thinking about ethnic difference than people in the West.
It is this ethnic difference that informs issues like the hanfu movement and the majority / minority divide in China, and potentially regionalism, as well, since Han could also be further divided into smaller, self-identifying regional groups with their own language and tradition. The bottom line is that you cannot assume that ethnic identity has no significance in modern China just because Chinese people don't think these differences are racial.
And you are assuming that there is a one way evolution; all people will simply want to adopt Han clothing and relate to a Han identity. People might just as well promote Qipao and Magua as they have for over a century and modify it to become the traditional Chinese national clothing. It is supra-ethnic nationalism that is gaining stronger grounds in this new age among professional intellectuals and grass root non-intellectuals, not Han nationalism. You can easily see this through the numerous attempts by Chinese anthropologist, however ridiculous, at trying to trace Mongoloid DNA in the Uighur population to prove they are related to the Han. This is also the same force behind denouncing Yuefei as a national hero and why history schools like the New Qing History is attacked fiercely in China. Han nationalism is largely restricted to the realm of amateur historians. Zhonghua minzu, not Hanzu, is the greater historical force today and it is the only way China can move if it ever wants to incorporate it's minorities into its system.
As for the development of the supra-ethnic Zhonghua Minzu identity, I am sure it will proceed, as well. Again, I want to emphasize that the two are not mutually exclusive, because Zhonghua Minzu is not an ethnic identity but an unifying identity for the nationalities of China. That was its official definition. Whether this identity can take the place of the individual nationalities, we can only guess; but as long as the Chinese government keeps promoting the "traditional" cultures and costumes of its minority nationalities, it is likely that ethnic differences will continue to persist and inform Chinese concepts of self, in which case movements like hanfu revival are to be expected because it fills a much needed gap for the majority nationality.
Finally, caution: while Han nationalism is more or less the domain of amateur writers in China, I think the situation in Korea and Japan shows that amateur writers can have a tremendous influence on popular nationalism, and even pose a significant political challenge to establishment historians and academics. Such a challenge maybe much harder to accomplish in China due to the government's control over the media, but I wouldn't write it off as a counter cultural force just because it isn't official. What typically causes ethnic nationalist movements to explode in power is the emergence of group grievances and conflicts, and unfortunately, there are such triggers in China - for example, ethnic violence between Uyghurs and Han, rural discrimination under the hukou system, biased economic development favoring certain regions over others, etc.