I was under the impression that Mao's unorthodox approach to revolution built on peasants rather than the industrial proletariat was and is seen, by the CCP itself, to be vindicated by their accession to power, and that that particular Maoist tenet was never really overturned.
I've never studied Marxism itself in depth, only come into contact with it in studying history, and it seems that you have a more in-depth understanding, but I thought that what Historical Materialism held about the necessity of capitalism as a precursor to communism was that in concentrating property and the means of production in the hands of the bourgeoisie, it oppressed the proletariat, giving them an incentive to revolt if they ever developed class consciousness, and caused conflict between different bourgeois groups (e.g. governments), causing capitalism to be completely unstable and necessarily bringing about its demise.
That is a very different chain of events to a communist government deliberately allowing a capitalist economy to flourish under its aegis. Capitalism leads to exploitation and thus unrest, but the most unwavering ideological pillar of the CCP is that the Party fosters social harmony and that it has an absolute mandate to rule and should not cede power. Deng himself made that clear when he decided to crush the Tiananmen protests, and the modern CCP has not budged on that front either.
Did Marx ever consider what a communist government who came to power before the full development of productive forces should do? Given that the reality Deng found himself in was at odds with the orthodox prediction of historical development, was his dialectical approach actually in line with Marxist orthodoxy?