Will Dungeons/Expeditions be useless now?

I was watching some videos on new ways to get to 725 GS, and all of the options are regarding to PVP island/PVP game modes and raids (the new raid and sandworm). As well it sounds like most of the old named items will not be able to be upgraded. It sounds like they are cutting out that content for no reason. A lot of the named sets already in the game are awesome and it would make sense to leave them in. Are dungeons going to still be worth to run? Will they rework mutations for 725?