So to start off, obligatory Nighthawk isn't getting replaced any time soon since it's more reliable than its counterparts at Kings Island and SFA respectively, but I don't see the park being able to easily get parts in the future since Vekoma no longer supports the Flying Dutchman model (though then again, Edwardo said the trains were re-done by Premier before the ride arrived at Carowinds). So with that out of the way, I present to you.....THUNDER ROAD DRAGWAY!
This coaster is an S&S Compressed Air Launch coaster, similar to Maxx Force. It would have the quickest acceleration of any ride on the east coast (and possibly North America), with the most double inversions of any ride on the planet (3). The ride would utilize as much of Nighthawk's infrastructure as possible, including the station and queue lines.
The elements in order would be as follows:
1. The launch. Maxx force hits 78 MPH in 1.8s, so we'll just add 2 MPH to that number and make it 80.
2. Also similar to Maxx Force, the ride travels into a "dog tongue" double inversion to start off the ride, reaching heights of 185 feet.
3. The ride would travel back down to the earth and into an extremely low overbank, flying over the midway like the similar element on Fury when it goes over the bridge.
4. The ride would go into the second double inversion, an immelmann & heatline roll maneuver (though knowing CF's marketing, it'd probably be called a "reverse snake dive" or something ridiculous like that). The inversion would be similar in shaping to the one found on Star Trek: Operation Enterprise at Movie Park Germany:
5. The ride would go into a cobra roll finale.
6. There would be three brake sections; an elevated one following the cobra roll, one that goes into a transfer shed near Nighthawk's old brake run, and one right before you enter the station. The total number of block sections on the ride would be around 6, allowing for four-train operations.
As far as the theme goes, it's a similar theme to Top Thrill Dragster. This gives this section of the park thematic continuity with Intimidator right next to it, creating a "speedway". It would also be taller and more visually striking than Nighthawk. The theme also allows for Thunder Road's name to be reused. As far as colors go, I think something like Skyrush
would be nice.