Barring WWIII, the ships (77 of which are "militarily useful") themselves would mostly remain in domestic trade.
If the Jones Act imposes a billion dollars in costs annually, that's ~$295,000 per mariner. $5 billion in costs annually means nearly $1.5 million per mariner.
National security is a fig leaf for what the law is really about: protectionism and keeping out competition.
#EndTheJonesAct