I'm admittedly very much not an expert in this area. But my post is less about the C919 specifically, and more about China's track record of developing manufacturing processes very rapidly such that they compete on the world market. Specifically I'm thinking of how China is suddenly exporting tons of EVs throughout the world at prices that USA/EU auto-makers can't really compete with. Over 50% of EVs sold in the world are Chinese (and none of those cars are allowed in the USA).
If China decides they want to continue developing and building commercial airplanes, where will they be in 5-10 years? Where will Boeing be?
China "cheated" with EVs. They never managed to make a combustion engine that could hold a candle against western ones in terms of efficiency and reliability. Electric motors are waaay simpler.
I doubt that the same will happen in commertial aircraft engines. If China catches up it will be through industrial spionage or very slow grinding, that will take many years.
This isn't 2010 anymore. PRC more or less caught up in mainstream IC drive trains. They prioritized resources on diesel engines (heavy equipment) it's essentially on par with global leaders and leading in some applications. Gasoline engine at parity for mainstream since 5 years ago, all the major brands has domestic power trains that's basically parity for mass market consumer vehicles, i.e. not extreme highend performance oriented like motorsports, because by then they pivoted to EV, specially because it would be retarded to waste energy on last 5% for high performance gasoline engines, and real secret sauce / aka hard stuff was batteries.
Commerical turbofan harder, but ultimately it boils down to TCO, where fuel efficiency "major" factor, major factor in that 10-15% less efficiency kills margins / ability to discout for current COMAC builds which uses many overpriced western components for certification. PRC switches to all domestic aviation stack (which they already have for military aviation, i.e. most of pieces there already), they can feasibly undercut/discount where PRC commercial aviation is competitive, it doesn't matter if CJ1000A is 15% less efficient than leading if upfront cost (+ favourable PRC financing) makes up for lifetime of less efficient fuel costs (cheaper TCO). But TBH civil aviation is not actually a "commercial" sector, it'a a strategic (geopolitical) sector, US will do everything it can to kill COMAC, or prevent global exports, i.e. no certification, sanction countries that buy COMAC etc.
Heavy diesel engines were dominated by the rest of the world in the 50s. Military aviation has no need for efficiency nor actual maintenance cost targets and thus, you have way more manufacturers of military than comertial engines.
My point is more that these domains seem civilizationally Hard. Western companies are very far in the effort/results curve. Will the Chinese get there? I guess at some point, though I doubt there is any incentive for the ICE motors in particular.
If China decides they want to continue developing and building commercial airplanes, where will they be in 5-10 years? Where will Boeing be?