百足之虫,死而不僵
Americans are still a long way from falling, and even when they do actually start to, their military at current strength without any new weapons will still top 3 in 60 years and more.
The way I see it China and US will eventually reach a new point where any confrontation, will be like cold war, in a unrelated country with no easy way of reaching the other without massive loses if even possible.
However, unlike the cold war, China AND US are both interdependent, very involved in the world, both huge economic powers, and envies of the world.
So this won't be a cold war, but it also won't be a one man show. A new world order is upon us.