That's an interesting question, but one difficult to answer, especially given China's current economic and other internal troubles. There are simply too many imponderables here to come up with a solid answer.
New Zealand Hmm, the next Empire will be formed out of several soveriegn countries that together they will be all empowering. It will not be the central and southern American nations, the USA will divert over seas action and influence to stop that kind of unity. The USA and Canada will not come together because there is simply too much anti-American sentiment for the USA propaganda machine (how massive and well oiled it is). The mid-eastern nations are too busy killing themselves over events that transpired hundreds of years ago. India and China will fight if one of the other threatens to become too powerful. Britain and France will never unite being just two to one nation (snails and fish and chips just don't cut it). Auzz and NZ with other island nations? I dont think so, population base is too low. I say Mongolia will saddle up and have another go. :roll:
The USA has a propaganda machine? I must say that, if one exists, I see little evidence of it. The media here are, as a rule, too busy putting this country down to function as such.