Mecha'thun is still in standard, and the cards you mention absolutely destroy it.
How will people kill off their own Mecha'thun anyway? You need extra mana (Innervate, The Coin) and a cheap method to kill the big boy. Warlocks have Grim Rally, but no coin generation. Druids have access to aditional mana, but they will lose their spellstone and Naturalize.
I guess druids can play Mecha'thun + 2x Innervate + 1 Biology Project (or vise versa) + Voodoo Doll + Moonfire, but that shit is counterable in my different ways as you said. Not to mention, in RoS druids will be vulnerable to aggro more than ever.
 I forgot, that Mecha'thun warrior is also a thing. NVM then.
I suggest you read Lazuli's Scheme again.
It hits ENEMY minions, not your own