Well the CPHC is showing a much different prediction in my opinion. They are predicting the track to come much closer to the islands than the NHC was with the storm maintaining hurricane strength for a much longer period of time.
So what will really happen with this storm?
Storm intensity is affected by wind shear and sea surface temperature. I cannot find a map that displays the wind shear patterns for the central Pacific (my link to the Navy Tropical Cyclone page isn't working at the moment). The prediction is that the wind shear will be increasing beginning today and that can certainly rip apart a cyclone depending on the wind speeds. If the straight line winds do pick up then that would certainly help to diminish the storm's intensity.
The predictions continue to state that the storm will be entering cooler water which will also drive the intensity lower. But looking at this map of sea surface temperatures from Weather Underground, the water temps look fairly consistent and warm to me.
Weakening of Flossie will occur, in my opinion if the storm takes a major jog north where the cooler water is. The current predicted path has essentially consistent or slightly higher water temperatures.
My uneducated assessment is that this storm will remain strong - at least a Cat 2 hurricane, possibly stay as a Cat 4 - and will curve north enough to create significant concern for Hawaii. This track puts the islands in the more intense NE quadrant adding to the potential for this storm to create some damage.