While you can sneak peak at the artifacts and jump happily about how cool you will be, ask yourself one simple question:
What will happen when the artifacts will have to be replaced by green weapons after Legion?
Clicking and adding the abilities in the calculator, I have noticed that the artifacts obviously touch multiple aspects of your gameplay, they are not about sheer numbers and spell power.
What I see is that Blizzard now happily constructs themselves a hell of a job to compensate everything they are now so happily forging into the “legendary weapons”TM.
IMHO the development team must start the “artifacts-have-to-be-replaced” brainstorm immediately after Legion is released.