Agnes Crane It just won’t go away, this needling worry about the U.S. dollar losing its coveted top-dog status.

No matter that there are plenty of reasonable arguments to support the dollar as the world reserve currency — namely there’s just no alternative — for perhaps decades to come.

Yet, in a world where once-rock-solid assumptions quickly turn to dust, investors should keep an eye on the dollar since changing perceptions are chipping away at its cherished status as currency to the world.

Much of the debate so far this year has centered on creating an alternative to the U.S. dollar, championed by China and Russia as a way to wean the world off its dependence on the U.S. as well as buffer individual nations against the missteps of those in developed world. Most recognize creating a new currency will take years and the chances of an existing currency, like the yuan, usurping the dollar anytime soon are remote.

But that doesn’t mean big money isn’t starting to prepare for world in which the buck isn’t the currency of choice.