According to a report from Reuters, it seems that Apple is expected to publicly share the trick the FBI used to hack its iPhone. In a way this is similar to a jailbreak in the sense that Apple already knows how it works, and that they are expected to patch up whatever security flaw that the FBI used to break into the iPhone.
They are then expected to share how this was done once the patch has been released, thus making it less effective and which could also send the FBI back to the drawing board and try to figure out another technique. It has been also suggested that the contractor who sold the FBI the information could just as easily sell it to another country or agency.
This effectively increases the chance of the information leaking, which in turn will allow Apple to identify the methods used and plug them before they get a chance to be used. According to a senior Apple engineer, “Flaws of this nature have a pretty short life cycle. Most of these things do come to light.”