Update: If you read carefully, the description is clearly related to the first Gear of War. Is this a sign that the remaster only includes the first episode with multiplayer elements from the other games? We will see...
Original story: The new Gears of War series website has just been published by The Coalition, leaking a great news right ahead Microsoft's pre-E3 2015 press conference.
Based on the Russian version of the website, which you can see translated by Google Translate below, Gears of War 3 HD is coming on August 25, 2015. This would mean The Coalition is working on a HD remaster of the entire Marcus Fenix trilogy and not only on the first chapter.
The announcement should be coming, at this point, on June 15, during Microsoft's pre-E3 2015 press conference.