Earlier, it was reported that a StarCraft FPS and an unannounced mobile game were canceled so that Blizzard could focus its resources on other projects. One of these projects is apparently Overwatch 2, which Blizzard is planning to officially announce at Blizzcon 2019, scheduled to take place from November 1 to November 3.
Details on Overwatch 2 are scarce at this point, but Kotaku's Jason Schreier has provided at least a little information on the game. In the same report where he revealed the canceled StarCraft FPS, Schreier said that Overwatch 2 will have a "large PvE element," which is a stark contrast to the original game that rarely features PvE modes. Schreier then added that some people at Blizzard have compared Overwatch 2 to Left 4 Dead.
Since the original Overwatch is a PvP-centric game, it remains to be seen how the community will react to Overwatch 2 focusing on PvE. One possibility that springs to mind is Blizzard could be keeping the multiplayer from the original game intact since it continues to be played by a significant audience, and use the PvE to draw in those who are uninterested in multiplayer games.
As for the Left 4 Dead comparison, that's a little bizarre. Maybe Overwatch 2 will be a prequel and be set during the Omnic Crisis, with players moving through a level and killing constantly-spawning robots Left 4 Dead style. It's doubtful that the comparison is because Overwatch 2 has zombies, but since we don't truly know anything official about the game, anything is possible.
Luckily, a clearer picture of Overwatch 2 should come to light by the end of the year. If Overwatch is announced at Blizzcon 2019 as Schreier's sources claim, then that means we will get our first look at the project in November.
We don't know how long in development Overwatch 2 is, so it's hard to say exactly how substantial the Blizzcon 2019 announcement will be. Schreier also said that it's possible Blizzard's plans will change and it won't show the game at all, so fans should keep that in mind as well.
Overwatch 2 is reportedly in development for unspecified platforms.