India and China: If they become superpowers, how long do you think they'll last?

Everyone's talking about India and China and their rapid growth. So IF they do become superpowers like the US, simultaneously destroying US trade, will they be able to last long? The US has been a superpower ever since WWI and became the strongest after the Cold War which is about 20-30 years. When these countries become the strongest, how long will they last? Or will it be like a rise and fall continous game?