According to screenshots of the support conversations with Motorola's customer care, put up by a website named Android Origin, Motorola will update the Moto X and Moto G devices to Android L once the OS is made available. When asked about the recently launched Moto E, the support representative wrote, "For the Moto E, we do not have any information as of today."
It is still too early to say if the information is correct or not, as Android L is still in developer preview and Google had made the developer preview source code available for Nexus devices earlier this month. Also usually when it comes to such information regarding firmware updates; customer care isn't the most reliable source of information.
Just couple of days back, Motorola India had announced it had started rolling out the latest Android 4.4.4 KitKat update for its for the Moto E, Moto G and Moto X smartphones users in India. The company made the announcement via its Twitter handle, and said users should expect the Android 4.4.4 KitKat update over-the-air soon.(Also see: Moto X Review | Pictures)