Gears 5 came out around 5 years ago. Considering the series has consistently rated very well, I doubt they killed it. They're probably just doing the modern AAA thing of spending a decade and a half working on a bloated game with unlimited budget. I bet we'll see one of those logo drops for Gears 6 soon (next showcase is in June), the game will release in a buggy/broken state with a flawless in-game store, the studio will get shut down, and then they'll announce the new Elder Scrolls game while everyone is pissed.

Microsoft didn't kill Gears of War out of ineptitude or malice. It's just that consumers don't want to play cover shooters anymore. There's no market for the game's core identity. People's tastes have swung hard in the opposite direction, they want movement shooters.