What decisions can you make now to avoid making emergency decisions later?
Don't forget the role that weather plays! In revising my syllabi for this semester, I had to revisit last Spring's... and the updates I had to make due to two bad weather days.
When the weather is so cold that electricity becomes questionable, moving to online alternatives won't necessarily work. One thing I've learned over the years -- and something I think you'd agree with given what I've read from you -- is that sometimes flexibility means just dropping an assignment and altering the total number of points in the course. I don't want to be an extra burden when students are trying to figure out a way to heat their homes. I know I could always post something for them to do later/asynchronously, but it's a delicate balance between trying to keep the class going and trying to give folks (including yourself) a break.
Great points for addressing these other emergency situations, though, and I thank you for them!