The next Gears of War title will run on Unreal Engine 5, and as a result, developer The Coalition will “not be announcing any new projects or titles for some time.”
The first four Gears title's were developed by Epic Games until The Coalition entered the fray with Gears of War 4, which was the first to use Unreal Engine 4; Gears of War 1-3 used Unreal Engine 3. Both Gears 5 and Gears Tactics also used UE4.
~The Coalition.As we look to future games, we’re excited to start shifting our resources to next-gen development using Unreal Engine 5. Gears of War has always been at the front of Unreal Engine development–as a breakout 720p title for Xbox 360 through last year’s 120FPS multiplayer update for Xbox Series X|S–and we’re excited to continue that tradition by developing on UE5 for multiple new projects in the coming years.
There's been several games that have announced as UE5 projects. Fortnite will make the change at some point, and Microsoft has confirmed that Senua’s Saga: Hellblade II will use the next iteration of the engine. UE5 is expected to debut later this year.
As for Gears 5, work continues on Operations 7 and 8, both of which will include new maps, characters and special events in the multiplayer mode. New content and “featured playlists” will continue being worked on till 2021, after which development will end.