AFAIK the water around the bridge is only like 50 feet deep and the ship itself is about 150 ft high. It wouldn't even really sink, just get stuck on the bottom. A crane ship would come unload it and then tugboats would pull it out.
The worst case scenario though does take a long time if it gets fully grounded and stuck beyond the ability of tug boats to pull it out. A company specializing in marine salvage has to come in to cut it up in place and haul the ship away piece by piece. They use large cutting chains that they pull back and forth to cut through the metal. It's a fascinating process: https://www.youtube.com/watch?v=Ndr2a7AQ8b4
In this case it seems the ship wasn't full, but it's not hyperbole to estimate it as being worth a billion dollars fully loaded. Cars aren't the cheapest things you can ship in containers, but they're far from the most expensive either, and they're what the Port of Baltimore specialises in.