I'm not sure that a fantasy game like Dungeons & Dragons really needs additional classes, maybe a guide to altering current ones to fit players wishes/demands for alternatives to the norm. It could include what abilities can be inter-switched to allow players to create new moulds rather than adding a whole new class with a fancy name. Swapping 2 cantrips for the heavy armour feat or dropping sneak attack but gaining great weapon fighting for example would allow players to tweek rather than stamp their character.
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I think 4e was a great version of the game, but in some ways it has muddied the water for the future of DnD with it's MMO attitude and the fact there are comments on classes getting nerfed or abilities being broken flying around the forums confirms this (to me).
These games exist to tell stories in the imagination, the change to a class should of course be balanced, but it doesn't have to be endorsed in a £30 rulebook to make it playable.
The plethora of sub-classes people want moved across to 5e, either as new classes or subclasses, is plain scary in my opinion.
If you can't take one of the 4 core classes and create an adventurer that fits the play-style you want you could perhaps go back to the drawing board and look at it again, or come here and ask for advice - with the creative energy floating around here I am sure any class could be made.