Current annexation laws make Castle Hayne extremely safe. For one, it needs to actually border the city of Wilmington in a signficant way to even be done forcibly. If you've seen the actual annexation study areas Kings Grant, Ogden, Springview, Masonboro, Silva Terra, and Dutch Square are the portions being looked at. Trends make it far more likely that high land value areas such as Figure 8 Island, Dolphin Bay, and Porters Neck would be annexed long before Castle Hayne is even considered.
Unless a land developer starts actively raising the property values along Castle Hayne Rd, I don't think Wilmington would even consider annexing it any of our lifetimes. The property value is amongst the lowest in the county and the infastructure simply isn't there to make it worthwhile.
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