Rebalancing the domestic economy toward greater household income is necessary to provide sustained growth in China, and that's what Michael Pettis argues in your link to his blog.
Make no mistake though, the national and Party leadership is deathly afraid of low growth and it is exactly what they seek to avoid. The leadership knows they must create domestic consumer demand and that this must happen through an increase in household spending or, as Michael Pettis notes, in spending on behalf of households. Low auto sales seems like evidence that this isn't happening quickly enough.
They can use the threat of trade war to convince others of the need for this shift, but actual trade war, or actual low growth? No thanks. When you are riding a tiger, you don't want it getting too hungry.
China has a long history of civil unrest, the Taiping Rebellion being a good example. Twenty to thirty million people were killed, and economic depression following a trade war was the impetus. The result of this horror was China on her knees, and is precisely what the leadership seeks to avoid.
https://www.facinghistory.org/nanjing-atrocities/nation-buil...
The return to authoritarianism can be seen as battening down the hatches before the storm.
Shifting spending to household income goes against powerful interests. A large national health program and social security could help, but debt funding is not an option now, and the alternative is taxing wealthy individuals and wealthy local governments. This also creates unrest.