My money is on China. Reason being that China's domestic policy (economic success) has determined her foreign policy, unlike most of the countries where it is the other way around.
China is strong, no doubts. But where their people will be leaving in the future? There are already territories on russian borders with china, where they illegally migrate and live. I think it's a good place for them to migrate....I hope no wars will be held. Does anyone have info on how China controls its population nowadays?
Fresh water is the next Oil. If Canada can dig up some vast oil reserves, breed further like dogs or us Indians, they are very well poised for superpower-dom. India has no hope , as we still follow poor agri practices and little rural education. What you see in India as richness is just pockets of glitter - just that.
You've got a point but a big chunk of Canadian population is composed of immigrants, mostly Asians. You need some nationalism to get the superpower thing going; with all these nationalities, its hard to see where will that come from.
I vote for upper Mongolia, we have to keep an eye out for those upper Mongolians or they may just rule the world some day.
From US vs USSR...the cold war has now shifted to US vs China... Currently China trails US..but this is bound to reverse in next 2-3 decades. India doesn't seem to have much chance... it lags far behind China in both military and economic strength.