Recent central bank behavior, including that of the U.S. Fed, provides assurances that short and intermediate yields will not change, and therefore bond prices are not likely threatened on the downside.
Most short to intermediate Treasury yields are dangerously close to the zero-bound which imply limited potential room, if any, for price appreciation.
We can’t put $100 trillion of credit in a system-wide mattress, but we can move in that direction by delevering and refusing to extend maturities and duration.