Quite how far the tastes of 21st century consumers will go in allowing the revival and expansion of sub-styles of Porter and Stout is anyone’s guess, at this stage.  A wide variety of new sub-styles already exist, with a few appearing to have staying power.  A skilled brewer can pick ingredients that conjure the flavour and aroma of chocolate, coffee, vanilla, liquorice or even plum.  Others pitch in syrups and essences that do the same thing. 

For now the subdivision of these beers into specialist styles seems premature, as they represent either a skilfully accented form of an existing style, or else an existing style with stuff put in it.