I don't think they're abandoning it, they are just going to hire a new team to remake W1 in Unreal Engine, while the core team works on new games using proprietary tools

Actually no, they announced some time ago that the next Witcher games (a trilogy) would be made with UE5.

their "own engine" I think is a euphemism here - its arguably several different ones. By many internal accounts, engine development has been hell (see the Cyberpunk launch issues), with each game CD Project Red start being in many ways a complete rewrite to the extent its not charitable to describe it as a single engine.

I think less time on game engine tech and hopefully more on shipping creative features sounds good to me, although it is sad to lose yet another independently developed game engine.

> with each game CD Project Red start being in many ways a complete rewrite to the extent its not charitable to describe it as a single engine.

That's normal and fully expected. You generally don't maintain an in-house engine the way general-purpose engines are maintained. You don't make it as generic as possible to accommodate for various uses, like Godot, Unreal or Unity do. Instead, you make games and then your engine is an optional byproduct of those games. It gets to be as specific to your game as you need or want it to be.