The next Watch_Dogs game is located in London. That's what Kotaku writes, without further proof. However, the website is not the first opportunity of that route. Previously, in the shape of a waterfall ugh, the developer Ubisoft Montreal seems to have already made himself.
The article by Kotaku is in one sentence concerning the next Assassin Creed. He says there was a excuse in "patch for Watch_Dogs 2 that the next game is based in London. And that's true". While the Kotaku will no longer support why it is so sure about the location of the next game, the site generally has good reliable links within the game developers world.
The talking advert was in place since February 2017. This expanded the video players see when they have played the game with an additional section. That's a audio recording where two voices are discussing steps against the player's groups. The lines on the screen, marking the London area of Brixton, can be seen.
Other posts say that they have released information about Watch_Dogs 3 also reporting that there will be little pressure on guns. That would also be appropriate in the UK, where it is harder to find firearms in the USA.
Tweakers has published a review of Watch_Dogs 2, published in 2016.