If you are a lawyer you are in the crosshairs
The world does not need the big fat American consumer. China took our manufacturing away, partly because you can't replace America as the preeminent power if you can't replace their manufacturing. The US is also an agricultural superpower. China cannot move that to China because you need the land, but you can be sure the agriculture is what they want.
What they have no use for are lawyers. Yes, they are big on propaganda, but they don't need American propaganda and they certainly don't need anyone competing with their own propaganda, so say goodbye to NYC and Hollywood. They also have no need for the tourist attractions of Miami. Most of our lawyers are in big corporations in NYC, LA, and Washington DC, so say goodbye to those cities. If you get rid of the major cities in the coastal US where 65% of Americans live then you don't need some of the ports like Houston bringing in oil for those areas. They can make this pipeline from Canada a major supply route for the heartland of the country.
If you think about it the only thing that China really wants is our farmland and you can't take over the management of the farms overnight. But you should realize that for China 30 million farmers is nothing, they have a lot of peasant farmers, they could easily bring in 30 million of them over a couple of years.
But what about the port cities? No, they don't need those. If you make Canada and Mexico your ports of entry it strengthens China's hold on all of North America while destroying all of the US ports will cripple the US completely as a world power.