Personally, having played the ever-loving-shit out of Legion content, I'm hoping for a lot of new cosmetics - such as new artifact tints.
If they go this route, the obvious answer for the geckos is to give them their DF legendary as an artifact, with new tints to unlock. I doubt the artifacts themselves will actually have the "ability and talent" components they did during current content (that'd be a nightmare with the current talent trees) so they'll all probably just be stat sticks that scale, same as the MoP cloak. Meaning the artifact for Evokers can literally just be handed to them via a simple quest and they're good to go.