Coal accounts for ~11.5% of rail volume[0], so they won't be screwed. (obviously not great to lose that much business) You might see prices drop due to a lack of demand, but other products will still be shipped via rail. Intermodal containers have been increasing in volume recently and I could see that taking up some excess supply.
Some containers go right from boat to rail, or maybe moved around the yard at the port to go from the boat to rail. Amazon may also have warehouses serviced by rail spurs, and not have to use trucking to get their containers from a rail terminal. I don't know if they do, but certainly some containers don't see any road on the way from the shipper to the receiver.
[0] https://www.aar.org/wp-content/uploads/2020/07/AAR-Coal-Fact...