Never in my life did I think I'd live to see a single currency used the world over. I just didn't think it could happen so fast or that all the disparate peoples would acquiesce so easily. Many believers taking the Bible seriously as God's Word have predicted that a globally common currency may be a prelude to the mark of the beast.
The Bible says the beast will control all commerce via this mark, and that those who don't take it will be cut off economically (and hunted and killed, but that's another matter). It has been long believed by many that a prelude to this mark would be a single form of currency. Admittedly, without central banking on a global scale (IMF?), directly controlling global currencies would be nigh impossible. This present crisis, though, provides a great excuse for the one-worlders to sacrifice all kinds of national sovereignty, to say nothing of individual liberties, in favor of a single, global currency. Once this is in place—central banking is assumed, as I don't see the world's kings giving up that power—the mark of the beast should follow easily.
You believers out there, will you be willing to embrace the difficulty of forgoing the beast's mark, assuming there's no a pretrib. rapture? Will you be willing to go underground? Your life as you've known it would end. You'll have to be in hiding. Perhaps an underground economy of bartering can be built, but it would need to be hidden from the countless who will take the mark (and surely be rewarded for turning you in). Are you willing to die for the Lord's sake? Are you willing to kill, too, to protect your loved ones from evil? Are you ready?


Maybe not
I wonder about the interpretation as a one-world currency. Somehow I don't think the SDRs would be passed on to the level of individuals to use as a daily currency. We're likely to have to keep on living with whatever inflation, devaluation, and usury our own central banks see fit to inflict on us, while the SDRs are used to bail out banks, corporations, and nations, preserving the investments of the rich and powerful by transferring real money from our taxes to their financial castles in the air as before. There'll just be more real money to replace the funny money that disappeared with the collapse of the derivatives, so that the rich can continue getting richer at a rate they can accept.
Or something like that.
Check out my free e-book Walkabout: The History of a Brief Century for a possible way the world might go from here.