typically, there is a weakening trend through the eyewall replacement cycle, sometimes followed by rapid strengthening. Therefore, this storm very well could drop into high-end Cat 3 range before landfall and not have enough time to restrengthen. The latest discussion from NHC certainly doesn't make it sound like they are very confident in their Cat 5 assessment right now. With evidence of concentric eyewalls and start of ERC, there's a chance that NO could dodge a catastrophic bullet tomorrow morning. Remember, the really strong SUSTAINED winds (>100mph) are probably only 15-20 miles outside the eyewall, with the Cat 4-5 winds probably within a few miles of the eyewall.