Are the Days of Coumadin Over?

I know someone on a personal basis (not a patient) who used to take Coumadin for recurrent DVTs. His INR used to go all over the place because he would alter his diet and start new medications that often interacted with Vitamin K. Back in those days, physicians used to dream about a magic pill that didn't require any INR monitoring and that would provide optimal anticoagulation to prevent DVTs. Many people are now wondering, "Is rivaroxaban/BAY 59-7939/Xarelto the first pill that will replace Coumadin and eliminate routine INR monitoring?" I'm very eager to see how other oral factor Xa inhibitors will compare. Is factor Xa inhibition the ideal mechanism? What about factor IIa? Direct thrombin inhibitor? The world of pharmacology is changing so rapidly that it's impossible to keep up with all these changes.