Interesting note: I have a friend in the airline industry, and according to him time-to-flight has no effect on ticket price. Rather, airlines assign prices to seats - and sell from the cheapest first. So theoretically if nobody buys tickets to a flight, it will still be cheap even the day before departure.
http://www.bing.com/travel/about/howWorks.do
(nee Farecast.com)
But even aside from that, prices go up as the cheaper fare classes get sold out. This isn't the airline raising fares, it is simply the cheap seats get sold out.
Finally, there are fare rules. The cheapest fares generally have 14 or 7 day advanced purchase requirements. So without touching anything, fares will go up at those time increments as the cheapest fares are no longer available, even if seats are still available. This is to protect the airline from selling cheap seats to last-minute business travelers with a high willingness to pay.
I can see that an event like this can throw the whole system out of whack. It's not obvious how the parameters should be altered. Without any data about how many people will buy more than one ticket in a situation like this, predictions are impossible.