Hurricanes are huge weather systems. From all gathered data the best central Florida can hope for at this point is a wet, sloppy mess and some unkown effect on park schedules -even if Irma turns sharply north and misses the FL coast. The meteorologists now are not just guessing in the dark. They have studied other weather factors and current systems, have live data from within the storm, and consulted lots of historical parallels to inform their insights. The science on this thing is real.
Having said that, I just hate it for everyone weighing whether to go on with trips this week. I've been at that point of decision before and it is no fun whatsoever when your long-planned vacation is at stake. In fact, as I recall it was a special kind of heartache. I'm hoping for safe and happy outcomes for everyone.