I would add that dungeons are dead in the sense that not only are they not being developed or improved, for the most part nobody really plays them much (though you can still find groups if you really want to see them). Raid may be dead in the "they're not currently creating any new ones" sense, they're still very much alive within the community and would be worth getting into if that's your thing. They also still give very good rewards (which is probably at least part of the reason they're still active). Fractals are the replacement for dungeons, are very active, and are definitely worth doing. If you want to look into what classes/builds are in the current meta, I'd suggest looking at snowcrows for raids, discretize for fractals, and metabattle for anything else.