I think it's about as clear as in the past, that given competent and properly-managed emergency response, 72 hours is generally enough. The long delays in this recent hurricane incident are due to political problems (I'll stay out of pointing at specific politicians) and the correct remedy is fix those problems. Like if your emergency plan involves storing five water bottles and when the emergency hits, four of them turn out to be empty, the correct remedy for the next emergency is make sure they're full. The incorrect remedy is to revise your plan to specify storing 25 bottles so you can deal with 20 of them being empty.