would you want a country other than the USA to have such power? This assumes that you must have the same imbalance of power and the superpower can’t be your own country.
I’d pick Brazil, for the reason that it’s almost impossible to imagine them causing any real problems with other countries, what with their multi-culti, hedonistic, tolerant, soccer-mad culture, weak government, and bureaucratic inefficiency. (Which begs the hypothetical question of how they could manage to become the sole superpower anyway…)
Then bring back the British Empire, I’d say. High tea and the Raj and Phileas Fogg and all that. We’d get along swimmingly.
I wouldn’t mind a united Europe as a world superpower, and I think they could become one if they got their act together. But so long as they continue to squabble, they’ll remain second rate powers at best.
The thought of a Chinese hegemony gives me the heebie-jeebies. They don’t take over a country so much as they replace its population with their own (see Tibet.)
I agree with Evil Captor, a united Europe would probably be best. As it looks, though, China will be stepping into that role sooner or later.
Sublight, you’re saying you’d rather have a united-Europe over the US?
A united Europe? No thanks. Europe does not have a great track record for this sort of thing.
If there’s going to be a superpower, I’ll take the USA.
I’d like to see a balance of power between the two. Even more, I’d like to see a balanced partnership between the two to act as a counterweight to the 800-lb gorilla that’s waking up China. US/Europe working together seems less likely to fall ass-backward into a shooting war that the US by itself.
Of course, an equitable partnership (which involves listening to others and making compromises) between the US and anyone doesn’t seem very likely right now.
Italy, New Zealand, Canada, or Thailand.
The country would have to be laid-back and/or more interested in wine and flirting than warfare.
Anyway, a united Europe is not a current reality.
The Aussies might stand a chance of making it work.
Canada, of course.
As an Australian, I’d go for New Zealand.
I’m-a go with Sweden.
Iceland.
What? I’m serious
I’d pick a Belgium that can turn invisible. Or maybe a flying Guatemala.
Superpowers are cool.
Holland all the way. Nederlands would just rock as a superpower.
Or maybe New Sealand ?
Thank you for your vote of confidence… but amazing as it may seem… my scantily dressed fellow countrymen are more prudish and conservative in relation to sex than you might imagine and a bit less tolerant than they appear. Naturally we would do a better job diplomatically than the US… we are a gregarious lot.
I myself wouldn’t mind a British Superpower (again). I like the way the Brits think and act. They are polite, sarcastic and intelligent.
I think the US has done a lousy job as the incumbent superpower. However, it’s only par for the course, it seems to me that any country that has the ability to become a superpower also tend to abuse it. Perhaps China is next in line, but I’m sure they’ll make a pig’s ear of it like everyone else.
I’m not sure if it was George Orwell that said it but whoever it was that did say:
“Power corrupts, absolute power corrupts absolutely” had it about right.
So, for obvious reasons I can’t nominate one country to be the next superpower.
But in the spirit of the question give it to Norway 
Japan or New Zealand