Rick Osterloh, Motorola's President, spilled the beans on company's plans about the next Moto X. He answered to a question on Twitter as part of the #AskRickO initiative. He was asked about the time-frame for the third generation Moto X.
Apparently the Motorola will be trying to keep an annual cycle for all its products, including the Moto X, which means we can expect the third Moto X to go official in August or September.
Earlier this year Qualcomm and Motorola revealed the company's next flagship will be powered by the latest generation Snapdragon 810 chip, which suggests the next Moto X might indeed use the Snapdragon 810 SoC. There are some overheating issues with this chip though and the current crop of flagships resolves them with a proper CPU throttling.
A cooler Snapdragon 815 successor is already in the pipeline, and the Snapdragon 820 is already official, so hopefully the Moto X will be utilizing S815 or S820 instead of the 810 model, no matter the earlier announcement. We'd hate to see another phone threaten by the user concerns for its hardware.