I cannot speak for HankFrank (and wouldn't quite frankly) but I can tell you that there are 3 conceivable reasons and forth that is more conceptual why "Wilma" may be weakened prior to a direct Florida strike.
a) Interaction with Cuba... I had a discussion with a person on here earlier where we were in a dissagreement about the amount Cuba can adversely affect hurricanes. The fact of the matter is, climatology suggest only "some" reduction in strength would be incurred should Wilma stray across.. The western aspect of the landmass has very low elevation - or not sufficiently tall enough to impede the large circumvellate of Wilma. Nevertheless, "any" interaction with Cuba would certainly punch a category 5 storm in the belly because at the envelope of intensity such as that, they ironically become prone to weakening at least excuse to do so.
b) Cooler water... Rita and Katrina have processed the Gulf loop-current and Gulf waters in general considerably. Should Wilma cross from those warm tuck waters that are between Cuba and the Cayman Islands, she will likely get a big, big shot of octane... But then, the waters on the N side of the Islands drops by as much as 4.5C by the time you get to the latitude of the Florida Keys... You simply cannot maintain even a category 4 storm under such conditions, considering that the U/A is also not cold enough to compensate for less potential instability (cold upper atmosphere relative to sst can sometimes offset for ssts of only 79F, a.k.a, Vince).
c) Shear... If Wilma goes ahead and evolves into a category 4/5 system and then starts interacting with veering steering field, those winds initially will be a hostile impactor. If she's moving smartly N before those winds are excited by the approaching s/w from the Nation's Heartland, then it is conceivable that she would not really be as adversely affected by them; moving along with the wind field means relative to the flow she is thus encountering limited shear vs. fighting those wind vectors off..

...The forth and conceptual notion was touched on, and that is that Category 5 intensity is seldom held for too long because it takes nearly perfect parametrics to maintain such intensities. Losing any one is bad. It seems that she will have a window to reach GFDL intensity, but then that window closes once the influence of said s/w NW begins to assert and influence over the Gulf as a whole.