Dataminers known as The Silph Road recently revealed on Reddit some new discoveries about upcoming features coming to Pokémon Go. In particular, the group said that by datamining through the mobile game's code, they found that third-gen Pokémon are likely to be introduced soon during a Halloween event.
The dataminers found a new loading screen teasing third generation Pokémon generation such as Dusclops, Shuppet, Banette, Duskull, and Sableye. Since this image is also Halloween-themed, it's likely that these Pokémon will be introduced this month.
Additionally, in an interview with Taiwanese magazine Business Weekly, Niantic CEO John Hanke confirmed that third generation Pokémon are "coming soon," but didn't specify when. The Silph Road have been credible dataminers in the past, meaning that it's likely that the Halloween timeline is correct. However, without an official announcement from Niantic about its exact release timeframe, we can only wait to see.
You can view all the findings from the datamine by heading here. For more on Pokémon Go, you can read about how legendary Entei is currently available in both North and South America for a limited time.