Epic Games were at one point the, besides their invaluable work on Unreal Engine, known as 'the Gears of War Studio', much in the same way Bungie were known as 'the Halo studio'. Oh what a difference a few years make, as both properties are now headed by different developers, and Gears of War being sold by Epic to Microsoft before moving on.
Before The Coalition got their hands on Gears of War 4 though, Epic did have a stab at the game for six months or so. As a man who worked at the studio when it was being worked on at both studios Rod Fergusson has talked about why Epic ended up letting the game go. In an interview with GameInformer (via GameSpot), he said:
Back in the days of Unreal Engine 3, [Epic] had this belief that we'd only build technology that we would use," he explained. So if Gears didn't need it, it generally didn't get put into the engine. That was from a perspective of, if we don't use it, it's going to decay. If we don't touch it, it will just rot on the vine and then we'd have bad code.
That's not how it was with Gears 4. Epic's initial Gears 4 engine was very mobile- and PC-centric more than it was console-focused. You can see their focus shift towards games like Fortnite and Paragon and stuff like that.
It certainly seems that Epic have a much different focus now, with the free to play Moba-like Paragon currently in the works. I say it is probably a good thing Gears of War got sold off, because The Coalition seem excited about the franchise. No need to see them try to fit a round block into a square shaped hole.