I don't know all the details, but aside from the things you mentioned, you will be working towards crafting legendaries in there, and also your class will be getting certain traits with a trade off. For example they showed that ele shamans can make their fire elemental permanent while not being able to use any of your frost spells, essentially making you a pet class with primal elementalist.
I think it's pretty cool that you can build something class wise like that. There can't be more variety really than that, it's a very fresh type of content, and just because it's 1-5 man, that doesn't make it the same as horrific visions. Look at m+, and look at mythic 0s. M+ is literally the same content just upscaled with a couple of affixes and a timer, yet it's infinitely more fun than a +0. I think that torghast could be a third pve endgame pillar if executed correctly tbh.