They released UT 3 in 2007 but I think around that time the company shifted more towards their engine, which by then was already the most used game engine for high profile games (don't quote me on that one, it's a gut feeling).

They started working on a new title, but it was meandering for a long time; it seemed that they would do some of the ground work but relied on the community a lot to design and build maps and weapons. Then the Fortnite team released a Battle Royale mode and made it free to play and it completely dominated the market. The UT team was transitioned to Fortnite in 2017, and Fortnite became their money printer earning them hundreds of millions per month.

While I love Unreal Tournament and would love for them or some other party to fill the gap of a no-nonsense arena shooter, the reality is that it wouldn't be as popular or lucrative as Fortnite. It'd be competing with FPS games like CoD and Battlefield, which have more going for them - including an uneven playing field, depending on players' progression and paid-for unlocks.