So, Tinker is still a possibility in the future. I think the question we have to ask is, will the tinker(AKA artificer) be a better addition to the game than additional specs or other favorite archetypes like the bard. Adding a new class is no small feat and it is a formal commitment to maintaining and supporting those specs indefinitely. That's a huge commitment.
The other question is, can you pull a dark Ranger and just add it in the game via cosmetic options? Not just for tinker but for any new additions really.