According to /u/NianticIndigo (verified as Niantic official), all Pokémon that are currently placed in a Gym will be returned to their respective Trainers. This process will be publicly announced well ahead of it’s start and Trainers will be able to collect coins the last day.
We’ll be sure to provide an advanced warning for when Gyms will be unavailable as we draw closer to the update. Also, it may be worth noting that when Gyms are temporarily disabled, all Pokémon will return to their Trainers. Stay tuned for more information! – source
Furthermore, John Hanke confirmed that Pokémon GO has been downloaded 750 million times in the past 12 months:
Smaller, but not less important, news
In addition to this, several details were clarified and debated in the past few hours:
- “Gyms will be disabled from June 16 onwards” – this was a mistranslation in the official Italian post, it was since removed from that version, but it’s still present in the Japanese post.
- “July 2nd is not the confirmed release date of the Gym Rework” – this was a date accidentally appearing on the German version of the official post, still not clear what it means
- The official image for the Pokémon GO FEST in Chicago features two oddities: Heracross and Unown (!). Heracross is not observed to spawn in that area and the ! version of Unown is not released yet:
- The previously reported advertisement in London and NYC were related to the anniversary celebration, as clarified by Niantic in their press release