Unless they get enough land for the Domination. They already got the population.
No, they don't have the population. They have 18% or so of the world's population. The Civ3 requirement was 66%; in Civ4 it varies but is always at least in the 40%'s. China is far from the population requirement for domination.
I still prefer Civ3's scoring method. It takes into account the strength of the civilization over all of, well, civilization. It seems rather silly that in Civ4 it's only the status in the very last year that matters in determining a civlization's greatness
. Surely, for example, the British Empire gives the British an advantage in the question of who is the greatest civilization, even though most of the empire in not British today.
If you go by CivIV's scoring method, China probably would win purely by population over the U.S., forgetting everything else. They only trail the U.S. by 0.3% in land area, so the U.S. certainly won't leapfrog China there. The only country with significantly more land than China is Russia, which as stated lacks population, so China probably would win by Civ4's scoring method. As to the wonders for the U.S. - they aren't
that important in the Civ4 scoring method, and population-wise the U.S. isn't even close.
They'd probably also win by CivIII's scoring method, for having the most consistently great civilization since 4000 B.C. India perhaps could challenge them, but I doubt with success.