That section of Route 47 lost most of its business in 1947 when the Garden State Parkway was completed. The rest of it went away when the Atlantic City Expressway opened for business in 1964.
Most Wildwood and Cape May traffic uses the Route 55 freeway, which is the replacement highway for Route 47, thus bypassing such dumps as Vineland and Millville. Traffic off Route 55 either takes County Route 550 or Route 83 to finish the trip on the Parkway. (God only knows when they'll finish the last stretch of Route 55 leading to the Parkway.)
Wouldn't closing an alternate route, regardless of how it's being used in normal daily traffic, create more issues during such a high traffic event?