It looked like Pacific Rim 2: Maelstrom was set to shoot this fall in Toronto, but that is no longer the case. As first reported by Latino Review and expanded upon by the Hollywood Reporter. The movie, which had been dated for 2017, has now quietly been removed from schedules, and there's a chance it won't happen at all.
The entire story comes down to tensions between Legendary and Universal, the studio to which the production company has gone after leaving Warner Bros. For the full details of that tension, check out this Hollywood Reporter piece.
Pacific Rim 2 was only happening because the film did well in China, and because Legendary has a "Legendary East" division that was created to get around Chinese quotas about foreign films. While China is attractive but not sure-fire for American studios (the way the profit split works out on movies released in China the studios only see 25% of the take. With dozens of screens being opened in China every week that small number could eventually get very, very big... if you're one of the 30 or so foreign films allowed to play Chinese theaters) it's a much better proposition for Legendary East.
But somewhere along the way the math stopped making sense. It's not clear if Universal's big year has made them less interested in taking a risk on Pacific Rim 2, or if, as The Hollywood Reporter speculates, movies like Warcraft and The Great Wall are causing the studio agita and they don't want to take on another movie that doesn't look like a surefire hit. This seems to be at least part of the reason why they let Legendary take Kong: Skull Island back to Warner Bros, where it will now be part of the Godzillaverse.
I honestly believe Universal is making a mistake here. Pacific Rim seems to really play to younger kids, and if the animated series Guillermo del Toro has spoken about were to happen I think the sequel would see a major increase in box office. The merch has done well, the film has done well on home video and there is a fanbase that would mobilize for a new film. I'm hoping somebody comes to their senses and gets Pacific Rim 2 back on track.