Personally, find this 100% agreeable. There's also no reason why any future Goblin- or Gnome-based Allied Races wouldn't be able to utilize this class, which technically expands their racial options to four (as DH should've, w/ Nightborne and Void Elves). If they then want to later expand the options, more power to them, but following DH it seems quite nice to have a class whose core membership all come from the same racial/cultural kernel.
Initially, I thought that the gameplay of a Tinker would probably follow a pattern such as this:
Pilot Mode (Generating Secondary Rersouce w/ Abilities) > Mechanized Mode (Spending Secondary Resource w/ Empowered Abilities) > Repeat
As I sat in Discord discussing it with a couple guild members, though, we ultimately came to agree that they could attain an equal level of distinction between both the two races (Goblin/Gnome) and the numerous specializations by designing around the use of claw packs, while also allowing the actual player's transmogrification to be visible. They lose very little of their thematic charm this way, but gain a lot (specifically, you won't see people complaining about not seeing their gear). After ~45 minutes of conversation, here's what I came up with.
"mDPS" | A specialization that relies on pummeling their foes with their mechanical fists, until they've gathered enough energy to empower those haymakers with a raw burst of energy (Gnomes utilize Electricity, Goblins utilize Fire). The appearance of their "claw pack" illustrates that they're built for hand-to-hand combat, with all the appeal of a brawler (bare hands, athletic poise, etc.).
"rDPS" | A specialization that utilizes a plethora of projected ordinance alongside two very massive, very powerful hand-cannons to terrify (and, ultimately, terri-FRY) anybody who would dare to stand in front of them and their goals (Gnomes utilize Electricity, Goblins utilize Fire). The appearance of their "claw pack" should reflect that they're built for a range, with a sleek stature and two cannons where you'd normally find hands/claws.
"Tank" | A specialization that engages his/her enemies with a monstrous mechanical shield in one hand, and a small sprayer (hose-fed) in the other. This sprayer is used to lather his/her enemies in a corrosive concoction (Gnomes utilize electrified "Shock Water", Goblins utilize self-heating "Hotspray"). The appearance of their "claw pack" should communicate that they're as sturdy as a missile silo, though simultaneously highlighting their use of chemicals offensively (meaning, the sprayer and the tank it's connected to need to look dangerous).
"Healer" | A specialization that focuses almost exclusively on formulating and dispersing tinctures on the move and utilizing a massive, two-handed liquid-cannon (hose-fed) to rain down extremely potent restorative elixirs on their allies. The appearance of their "claw pack" ought to reflect their non-combative nature, with the more pronounced features being the tank that stores their healing extract and the enormous dispersal cannon connected to it.
The two specializations highlighted in orange deliver on the "Tinker" fantasy.
The two specializations highlighted in green deliver on the "Alchemist" fantasy.
A few related images and what they're related to:
"rDPS" cannons might look something like this:
https://cdn.instructables.com/FH8/G3...I4X1.LARGE.jpg
"Tank" could look a lot like this, minus the hand-held potion:
http://www.lol-wallpapers.com/wp-con...egends-lol.jpg
"Tank" could utilize a weapon similar to this, spraying liquid instead:
https://i.kinja-img.com/gawker-media...fxoatkmpt4.jpg
"Healer" could look something like this, replacing a lazerbeam with an elixir shower:
http://imageslogotv-a.akamaihd.net//...=jpg&width=480