Even if it weakens to 120 mph as it gets within 400-500 mph of the East Coast, that is extremely problematic. Recall that Hugo was a Cat 3 storm as it approached South Carolina, and then jumped quickly to Cat 4 as it went over the Gulf Stream as it closed on the coast. The same could happen with this system if it closes on the coast anywhere south of Wilmington, NC.
As I recall Hugo moved up the coast from a point east of Jacksonville, sucking up energy from the gulf stream as it did. Hurricane warnings went up in Jax, then Savannah, then Charleston, then Georgetown. The "predicted path" cone was revised northward every couple of hours. Lots of folks were caught totally off guard.
The strengthening wasn't predicted either. Lots of people just shrugged it off as "a small one". "Besides," the old-timers said, "they never hit here."