The existence of something within a story doesn't necessitate that the audience will view it as reasonable -- which is where we're having a disconnect.
It seems as if the bedrock of your position is something akin to, "it exists, therefore, it should be implemented as-is regardless of how well it will play with the broader playerbase". Which is problematic and, well, hasn't been done with any class previously added post-Vanilla. They (Blizzard) seem to always be shooting for a general appeal (as opposed to a specific appeal, or niche appeal) because that's a good business practice. No reason to assume this practice would change now.
(Edit: Which isn't to say that Tinker is in any way terrible, just that the iteration of Tinker being asked for by many of the loyal proponents is... far to niche, from a fantasy standpoint.)
Yes, I understood your point, I just don't think that the conclusion is supported.
That some previously untouched Tinker NPC's were equipped with some existing assets to imply association isn't really indicative that the FM-style Tinker is Blizzards go-to conceptualization -- especially with Gazlowe's HotS model being newer, conceptually, than Mekkatorque's. The only thing implied by this is that Blizzard wants people to recognize Gazlowe and Marin (and others) as being Tinkers, visually.
I wasn't really speaking to what Blizzard would/wouldn't do -- obviously, they'd be able to handle implementing whatever they wanted from a technical perspective. That said, they're almost guaranteed to never implement this class as the vocal, dozen-strong fanclub wants them to.
What I was saying is that there are obstacles to implementing the class, "as-is", and I question whether doing it would actually be a net benefit to the game. The PM-style Tinker would assuage many of the concerns (not from players who enjoy Tinkers, but from players who don't) about the game becoming too... far-fetched.
It's odd that you keep saying you're disagreeing, while saying the same thing you quoted from. Not sure how to respond -- we both agree, they're never going to in enormous suits, even if they're in said suits full-time.