i'm not a fan of just replacing the Artifact Weapon with another all mighty weapon. This would just mean our Characters are worthless without the weapon. And shouldn't it be about the wielder not the weapon? I think the Outlaw Rogues Weapon dealt a little with it. All the "Power" of the Artifact were actually accomplished by their wielders, but no one would thought that this would be possible so they blamed/claimed that the weapon has the power.
so i'm all for green lvl 111 weapons in the next expansion. Also more Weapon Transmogs to use among all classes instead of locked to specific classes
If we want a gameplay system similar to Artifact weapon there are simple solutions like the Path of Titans, remember that? Or what i would favor, Lets get back our old Talent Trees!, kind of. Let's call it Mythic Talents. It's not replacing the current talent system, but works similar to artifact trees. but you can use all of your new Mythic Talents on any spec.
Say you are a Blood DK, you can spend Mythic Power into the unholy Mythic Tree, to get permanent minions too.
Or as a Disc Priest putting Mythic Power into the shadow Mythic tree to get more damage options, put Mythic Power into the Holy Tree to get more healing options or remain in your disc mythic Tree to get more and better barriers and shields.
A BM Hunter who doubles down into BM can get 3 pets, 4 pets, 5 pets at once. while MM and Surv could spec into BM to get 2 Pets
A Prot Warrior could spec into Fury to get the ability to use also twohanded weapons in one hand. Spear and Shield!
of course such a system wouldn't be exactly the same as the current one as it should not be able to max out every trait in it.