Too lazy to search for the exact link but I seem to remember reading some editorial in the financial section of The Economist about 3-4 months ago where they were saying that bonds are sort of cash-like, or were sort of cash-like when that article was written and when the papers on which that article was based had been written. If that premise were to hold true (even in part, meaning bonds are sort-of-cash), maybe most of the "rules" economists have written down until now when it comes to the cash vs. bonds relationship would need to be re-written.
For the matter, I don't take much of what it's written down in The Economist at face-value anymore but their financial stuff is still pretty spot on.