This is stated in an article on the gaming portal Eurogamer: “Blizzard announced last night that October 2 will be the last day of work for Overwatch 1 (due to time differences it may be October 3 in other parts of the world),” the article reads. “Then, Overwatch 2 will be released on October 4th and will be the only active Overwatch game.”
“About a day before the launch of Overwatch 2, we are going to shut down the Overwatch 1 servers,” explained Chief Commercial Officer Jon Spector. “So October 2nd will indeed be the last day you can log in and play Overwatch 1. Then we are planning a 27-hour break to prepare the Overwatch 2 servers.
We will give current Overwatch players the option to download Overwatch 2 a little before we launch if they need to preload. There are also a few things we’ll be asking players to do to prepare for Overwatch 2. We’ll be sharing a sort of pre-launch checklist with players ahead of time so they can log into the game on October 4th without any problems.”