The Irish Potato Famine comes to my mind.
Why?
classic case of monoculture.......... did I hear "VIRUS"?
lack of species diversity
The reason we don't learn anything from history is because those that can make the connection have a hard time explaining it to the analogously challenged. Some of us can remember when IBM was 75 or 90% of the computer industry. Until they lost the plot. Trouble is uncle Bill was the guy who hid it! Not until he finally steps down will we see MS go soft enough to belly-up. Unless there is a PC blight (like a virus but we won't be prepared for this twist!)
I predict both but I can't give a timescale, if I could I wouldn't be telling everyone - I would be laying the bets now.
the problem with monoculture is that so much of the world is geared-up to it. If you are looking for my kinda work you dun gotta be Office literate. "Can learn" equates to the "NO pile".

just a thought but MS & ME are both pretty debilitating ilnesses.