This depends on the taxing jurisdiction. In some cases "property" taxes as levied statewide based on the total "value" of railroad property in the state, and then divided amoung the individual jurisdictions on some basis. So if a branch or some property is abandoned it does not necessarily reduced total taxes, only move them around. However in the case of a shortline like the D&S, there is greater likelihood that taxes will go down. This is a complex issue that I am over simplifying and varies all over the place, and over time. Like most tax stuff it might make sense at some high level, but by the time you get down to the nitty gritty there is little obvious logic.
JBWX