I just looked at all historical tracks from 1920 to the present for all Cat 4&5 hurricanes in the Atlantic that eventually made on the southeast US coast (not necessarily at those strengths).

The good news is that according to the historical data at the ibis site, no Cat 4/5 hurricane has ever been as far north as Ike is at this point and managed to make landfall in Fla, GA, SC, or NC. The bad news is that hurricanes will continue to make history, so there's always a first.

Isabel came very close to being as far north as Ike. And both Dora and Andrew, were both as far north as Ike, where he is predicted to be tomorrow. They both swung up from the south toward the north and continued further north while Ike is predicted to be pushed well south of their tracks. But Ike will be the farthest north at this longitude if he makes landfall. Interesting!