Call of Duty 2023 is Reported to be Revealed in August, including Zombie Mode.
According to Insider Gaming's Tom Henderson, the Call of Duty 2023 will be revealed in early August which is currently set for August 1st. Just like its predecessors Call of Duty Black Ops Cold War and Vanguard both revealed through an in-game event, it's likely that the Call of Duty 2023 get the same treatment in Warzone 2.0.
Aside from that, Insider Gaming also reports that Zombie Mode will differ from the traditional round-based format as that formula has received negative feedback from players in Call of Duty: Vanguard. Therefore, it's possible that the new Zombie Mode will feature a different experience made by Treyarch.
This is all speculation at the moment, so please take this information with a grain of salt as there's no confirmation from Activision.
Source: Insider Gaming