Call of Duty: Modern Warfare will release on 18 October 2019. The leak of the release date along with box art and some minor snippets is courtesy of Activision themselves, perhaps intentionally, mere hours before the reveal stream.
Call of Duty: Modern Warfare reveal live stream was just a few hours away from the time of writing this article but the release date leaked through Activision's own YouTube channel when the upcoming video popped up. It reveals that the new Modern Warfare will come in October 2019, with many believing it will be on 18th.
We can't tell for sure though as the captured image is fairly blurred and fans have reported seeing 13, 18 and 22 as the possible release days. You can check it out for yourself. If nothing else, you can see the box art and possibly count the pixels.
The fact that the video popped up conspicuously just hours before the live stream that would announce all those details points to the possibility that the supposed leak could have been intentional in order to hype up the gaming community and grab as much attention as possible for the premiere.
It is also not impossible that the release could be pushed back, just like Call of Duty: Black Ops 4 was so Modern Warfare's planned release date is not written in the stars. Depending on some of the bigger titles' release dates that will be revealed at E3 2019, Activision could move their title to avoid losing sales to other giants.
That's exactly what happened last year with Black Ops 4, except the later chosen release window of November is occupied this time around since Sony announced Death Stranding's launch.
It remains to be seen whether this Modern Warfare will build upon the story presented in the previous games or reboot the series. Hopefully it remains in the same universe, there are definitely some fan favourites like Soap, Price and Ghost that players would love to see again.