Sure, if you limit it to two things that are either unrelated to the Tinker concept, completely ignore the theme, or you use your own biased and limited view of what an ability could do.
Let's look at healing for example. Why are we talking about "injections" when Blizzard could simply base the healing spec on the Goblin Alchemist hero from WC3 and combine that concept with a few abilities from Blackfuse and Mekkatorque?
Healing Spray: Sprays the area with a magical spray that heals your allies and repairs your devices. Spray lingers in the area for 3 seconds before dissipating.
Unstable Concoction: Lobs an unstable concoction at a targeted area that heals allies and damages enemies in its radius. The longer the button is held, the more healing and damage the concoction will do. However, at max charge, the concoction has a chance to explode, dealing damage to the caster!
Bouncing Elixir Blast: Blasts a target with an unstable elixir that heals/damages an ally/enemy for X. If the elixir crit heals/damages, the potion will bounce back to the caster, healing them and adding an additional charge. (2 charges, 25 sec. recharge).
Heal Bot: You deploy a robotic assistant that heals nearby allies for X%. Robotic assistant lasts until cancelled.
Shield Generator: (passive) Standing near a turret reduces the damage you or an ally takes by X%.
Medical Bay (Replaces Pocket Factory): Deploy a medical bay that constructs and launches healing robots that heal nearby allies. At end of the duration, healing robots leave scrap.
Andrenaline Bomb: Increases the attack power and movement speed of a target for X seconds.
Transmute: Turns a party member into gold, increasing their armor by X%, and removing all disease, poison, and curse effects. For the duration, all healing effects on the target are increased by X%. (CD)
Looks like they're bringing quite a few new things to the table. Interesting considering that healing has the least amount of available compared to DPS and Tanking.
Heck, I'd even have the healing spec ride on the back of an ogre like it does in WC3;
And with the ogre, you can get abilities such as;
Ogre Pack: (passive) Your ogre allows you to carry additional items.
Chemical Rage: Induce your ogre into a rage, increasing movement speed, and slashing nearby enemies with its blades. Damage done by your ogre heals nearby allies. At the end of Chemical Rage, damage done by your ogre increases your healing ability based on the amount of damage done for X seconds.
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No. The Tinker concept is too large for a class skin, and no class is even close to its theme.
It isn't like Witch Doctor and Shaman where you can simply add a few voodoo totems and call it a day. Tinkers are fundamentally different than any other class in WoW. The introduction of Evokers has little to do with the possibility of Tinkers. The game still lacks a technology-based class given the abundance of technology within the gameworld.