What you said about not quite knowing how much to change and what time frame to use is the scariest part to all of this.  We're stuck having to play a guessing game - trying to guess how many donors will remain and how many will need to drop (regardless of how much they love a mission / programs).  So, for now, I'm stuck just obsessing over how to predict the future (which is impossible). 

Over the next year, I've at least decided that we're doing more work with education hoping that at least our public schools won't see cuts - they've got the steady stream of public funds available.  I don't see this changing even in the worst of times.