Based on the logic from the railway mappers and railway lifecycle, it should be left on the map.

If they can keep their no-longer-existing railways on the map, than gosh dang it, I want to keep all these long-gone roadways!  It's the same thing, and if you squint your eyes enough you can see the a somewhat straight line that indicates a road must have been here!

In all seriousness, I see no remnants.  I went ahead and removed it.  Unfortunately, there are many other "abandoned" railways with no traces that have been overbuilt but are continuing to be added.  My changesets to remove those have been reverted, and I am sure it is only a matter of time before someone reverts this changeset...