Sources say it will have a free standalone version too.
Call of Duty: Modern Warfare will supposedly get a battle royale mode in March 2020, according to sources who spoke to VGC. The sources, who are apparently part of the US development team, said that the new mode is "at least a few weeks away" and, unless there are unexpected delays, will probably launch in early March.
The battle royale mode will be called Warzone and will be available to all existing Modern Warfare players. It will appear in the main menu where an option is currently listed as "CLASSIFIED." It's also said that the battle royale mode will be available for free as a standalone game but players of that version will be able to upgrade to the full version.
Apparently, the battle royale mode will have unified progression with the existing battle pass too. That would mean that any cosmetics you've unlocked already will carry over to the battle royale mode.
Finally, VGC's sources say that we'll hear more about Warzone this week. That's due to North American content creators reportedly having been invited to play and capture footage of the battle royale mode ahead of the announcement.
These rumours come after a week of leaks that seem to all point towards Modern Warfare getting a battle royale mode called Warzone. It all started when Activision announced the game's second season with a cinematic that included soldiers dropping from a plane onto what seems to be a larger map, surrounded by gas. All vital elements that go into a battle royale map and mode.
Dataminers then got to work and discovered files pertaining to something called Warzone. Meanwhile, some players accidentally found their way into the map seen in the cinematic via a bug. Hopefully we'll find out if any of the leaks were at all accurate soon.