The ferry system was heavily reduced after the bridge was put into operation. It can be revived, but not overnight. Ships, including ferries, are a valuable asset; if they don't make money on a route A <--> B anymore, you will sell them to work elsewhere, possibly thousands of kilometres away. Getting them back in case of need is not easy.

Civilian ferries are no match for military logistics anyway. Transporting some people, food and cars via a standard ferry is fine, even though you can expect bottlenecks and long waiting lines. Transporting 500 tanks is a whole different thing altogether.