I don't disagree. This was a very lucrative market for GM, but like all things, it is coming to an end. For more context, 50% of GM's operations are in North America, 30% was China, and 20% is the rest of the world. The China market is very important to GM, but I think they know that they are very unlikely to stay competitive there. A gradual wind-down to its China operations is likely which means North America will be the last market where GM has any significant presence in.
I'm not sure if GM will pull out completely, but they will definitely have to reduce their presence there (China) since it's now a loss-making business.