The key word is 'SOON'. It communicates a prediction that China & Japan will decrease their holdings of Treasuries while the Fed's holdings increase. Sometimes securities strategists predict stuff, and articles are written.
You can debate about the merits of the prediction, but getting caught up in a 'gotcha' on basic addition is pretty disingenuous. Unless you suck at reading comprehension.
Soon? Doesn't sound like a very precise prediction. I didn't see anything in the article about anyone decreasing their holdings. Maybe you were reading something else?