Another concern that y'all seem to be missing is: How do you move that many people in a speedy manner?What was it, 50000 people in roughly 100 floors? So about 500 people per floor?
How fast can you put another person on your escape route? Every 5 seconds or so? So it takes 2500 seconds, around 40 minutes, to get everyone off of one floor?
How long does it take you to get down one flight of steps? 5 seconds? 10 seconds? Multiply that by 100 flights. From the time you decide to leave, even if you're the first one to decide, how long will it take you to get to the bottom? And that's if you don't have people from lower stories blocking your way down.
On shorter multistory buildings I've seen various fire escapes - ladders, stairs, tube slides, tornado slides, stretchy cloth tubes. None of these work on larger buildings for various reasons. Could you imagine riding a tornado slide for 100 stories? I'd puke before I got 5 floors down. Not to mention how hot your butt would get from the friction.
Another thought for designing the escape plan.