Two years ago a war would absolutely murder theme park attendance, as most guests would be flying to WDW and the greater Orlando area, and most of them would be flying in internationally too.
But after September 11th, the international market is all but dead, and has little to no hope of ever recovering to previous levels. On top of that, the number of guests flying into Orlando is down tremendously. Disney, Universal, and Busch have offset this by increasing domestic and local attendance (well, Universal and Busch have, Disney has pretty been been along for the ride with the current travel climate), and these travelers have been driving into Orlando, rather than flying in from out of state or even out of country. Now don't take this to mean that there aren't international visitors flying into Orlando, there still is a good number of them. But it is a mere fraction of what used to fly in. Heck, even domestic air traffic into Orlando will probably never full recover for another decade.
For all of these reasons, I think that the "catastrophic drop" in attendance that Disney is warning about is more of a nice smokescreen to soften the fact that attendance is dropping anyway at WDW. There will certainly be a drop in attendance at the Orlando parks if we go to war with Iraq, but because of the shifts in tourism, it will be nothing like the drops we saw after September 11th*. That catalyst has already occured.
* The sole exception to this is the international market, which will all but cease to exist in Orlando for the duration of the war, if it were to ever happen. Fortunately, international tourism occupies a smaller slice of the pie than it did two years ago.
But Im with you... we have two more trips planned for the year.. war or no war, we are going.. Im with Disney till the very end. 
