I heard on local DUS radio last week that there will be modifications (=enhancements) to the S-Bahn service covering the airport. The radio comment mentioned that the S-Bahn Terminal station will no longer be served in future and all trains will go to the long distance stations, thus pax will need to use the Skytrain to get to the terminal.

As I am not so familiar with the different S-Bahn lines I am not sure what the press weasels are saying...but I guess the radio comment was correct.