The scientific community has made it clear that a reversal of the earth's magnetic poles is inevitable. They just don't know when. As the research matures they will start predicting a time-frame.
When the worlds population begins to react some of those in power will begin to foment denial movements in order to give themselves more time to secure their own financial and physical survival.
A story that captures the political and financial intrigue, military actions and religious reactions might be something to get an authors long-term muse interested in. It might make a good allegory.
A shorter story could focus on the time just preceding the event or post event. From my research it has the potential to be apocalyptic. You could probably get away with making it as apocalyptic as you desire.
This, like my other story suggestions, is just a seed. It might grow and it might not. I'll look for a story when/if I see one coming. But I wont quit planting seeds. ;)