IMHO, Mike may have used the common term GPS to suggest to those attending, the possibility of a LPS (layout positioning system). Using sensors like those now available from Lionel, the DCS system could, at some point, sense and react to where trains are on the layout.
Not quite 'global', but within the confines of a layout, it would serve as a GPS.
Who would have thunk 20 years ago, that half the stuff in a DCS system would be available?
Ed