They are habitable with the correct building codes. Northern Florida historically got very few hurricanes so the buildings are not hurricane resistant. The fact that their house floated away is the red flag that the home could never survive a hurricane. Houses in South Florida are concrete block exteriors. In the Keys you can't have any living space at all on the first floor too.
It does make it much more expensive to build but I see that rule becoming necessary in all coastal areas.
The extreme damage will be when hurricanes start making regular landfall in even less historically hurricane prone areas (see Western NC getting hit by the same storm at a fraction of the strength it hit Florida with). We already had hurricane Sandy fuck up NJ. It won't be pretty when a similar storm hits Philly, NYC, DC, etc.
What surprised me most about Helene was the ground speed. I don't remember seeing any hurricane make landfall in the US moving at over 20mph. As a casual observer I have anyways seen 12 mph as a quick storm and 6 mph as slow.