That's just one side of the story. While the success of Fortnite definitely played a part of the cancellation, no one really cared about the Unreal Tournament reboot. It got no traction at all. The game was playable but had no players. And while there was a big interest of a small group, it got no interest outside of that group. I think that even if Fortnite wouldn't have been as big as it is, Unreal had no chance because the gaming demographic changed and there is no demand for a game like UT anymore.
Arena shooters in general are kind of a dead genre. Quake Champions, Diabolical, and a few others all collapsed. Even Halo Infinite couldn't sustain a player base.
Halo Infinite died because Microsoft mismanaged it. They had huge player numbers at launch but they failed to keep the content going and people moved on. They couldn't even manage a tie in with the stupid halo show when it launched.
Their complete lack of interesting custom games is what killed it for me.
Halo, for me, was about forge and messing around in fun game modes people came up with. Releasing Halo without forge and with bare bones custom game tools is like selling a car without seats.
Yeah, they claimed live service and I believed them, but forge was released a month ago and I can't muster up anyone who wants to play anymore. lol. I can't even get my bro to play through coop. Bums me out because halo was my jam almost my entire life but they can't be arsed.
Halo infinite failed because literally half of it's content was garbage. A bunch of new guns, most of which sucked, a bunch of new maps, that weren't impressive, and genuinely game modes that were so boring and bad, my friends and I gamed them to get them over in a couple minutes instead of the normal 30 minutes it would take to play out.
It was also really glitchy, really poorly optimized, and full of GARBAGE microtransactions. It was like multiple tens of dollars for a different set of armor, while previous halo games arguably pushed cosmetics as an awesome thing and an actual status symbol because you couldn't buy them, only unlock by completing challenges.
It didn't get "no interest" it got people dipping their toes in waiting for it to be done.
I played it, and enjoyed it (I played the living daylights out of UT 2004 and UT 3, and was eager for UT 4). I was waiting for the single-player portion of UT4 to be in a cleaner state. It was the only reason I signed up for an Epic account. But UT 4 stayed in rough shape with unfinished features, though it was playable.
I doubt I'm the only one that was tracking it and watching games like the newer (and amazing) Doom come and go.
I hope they open-source all the assets and maybe the existing game code like they've done with some other cancelled titles. It would be cool to see the community finish it or build something from the ashes