China is a communist country. It cannot have a middle class.
It has grindingly poor people, and it also has relatively affluent people. Plus some very, very rich people. Mao wouldn't approve. China's middle class (the affluent ones) live disproportionately in the coastal provinces.
I don't think China is handling the wealthing of its society terribly safely though. I'm guessing here but given the lack of devolved power in China, there might really be a rising under a second Mao, and a confiscatory grab/bloody revolution by the impoverished internal provinces of China. Much more likely is the continuation of the current de facto separation between the coastal provinces and landlocked China, policed by the Red Army - and then a formal separation into Nu-China and Poor-China in a decade or so. IMO
Which is why they will not remain communist. Nothing undermines authoritarianism more effectively than the first taste of prosperity.
Should a communist country have Free Enterprise Zones? Are their citizens buying their own apartments? Did they decentralize their agricultural industry? Are individuals allowed to own their own businesses and profit from them?
Oh, and btw, China has a rapidly expanding middle class.