Moto has just announced new Moto Mods for the Moto Z phones, We already know that these Modules will be compatible over next three years.
Amazon Alexa Mod:
Amazon Alexa Mod brings Alexa with you everywhere. You can easily perform everyday tasks while on the go, like controlling your smart home, checking the news, requesting a ride from services like Uber, and more — using just your voice. For example, when you start your commute home, you can ask Alexa to adjust your home’s temperature so it’s comfortable when you get there. Or, you can add milk to your shopping list without ever picking up a pen.
Along with the Alexa Moto Mod, Motorola also introduced "turbo charger", which charges your Moto Z quickly, "Moto Power Pack", which adds 50% more battery to your phone. A Gamepad Module which adds gaming controls to the ends of the phone to give you a full gaming experience.
Update: Here's the Robot Mod
Source: Moto (Cached)