The only thing that truly makes your point is the logistics. In order to have a face to face battle, either side would have to move vast amounts of men and supplies over the Pacific Ocean. Which means, while they almost certainly could beat us in open battle, that will never happen, just because of logistics.
For those interested in truth, the North Korean army had taken all but a tiny beachead in S Korea when our counterattack destroyed the NORK army.
Later the Chinese army invaded S. Korea only to be thrown back out again by US forces.
The US has a well established history of beating the sh*t out of the Chinese army in open battle.