Most Railway nomenclature like "Sampark Kranti", HumSafar[which is just a rebranded updated version of GR], Duronto is a gimmick. Every Rail Minister wants to leave his imprint and in the process starts his own flagship train. A logical system would be to reclassify the current system into a minimum required system[for eg, Duronto and SamparkKranti is just a SuperFast train and should be classified as such; GaribRath is just a subset of AC train]
In my book, Passenger, Express and Superfast should cover most of the categories. Full AC trains can be...
more... called as AC Express or AC Superfast as applicable. Only Rajdhani and Shatabdi remain with their own names. It creates a much more rational way for a passenger to understand than the myriad mess that currently is.