Ok so recent interview had this quote about progression:
Players often say they have the most fun during the start of the expansion when there is so much to do. After that the progression options narrow, as the main focus is on increasing your item level. Artifacts are an alternative path that keep things interesting and relevant.
So basically
raiding = item level
everything else = artifact level?
If this is true then I would be very disappointed that they are continuing raid or die model