Just to muddy the waters, I will add that there are actually TWO kinds of pole shift:
One is the change in magnetic poles- this is what's causing runways to need renumbering as they are named by their compass headings. Magnetic pole shift is constant and can be compensated for over time.
The second is an actual shift in the earths rotational axis which has been present but relatively stable for at least all of human history. Any geologically rapid changes there could be cataclysmic indeed! Let's hope it doesn't happen.
More on this second type of pole shift: