I think Godot catching up to Unity is pretty likely within the next 2-3 years. Unity is a mess of tech debt, mismanaged, and has just burned all their good will. Godot should be able to improve much faster due to the lack of tech debt, and a lot of indie devs are motivated to help.

I agree that catching up to Unreal is not going to happen any time soon; they're way further ahead on rendering features, and constantly improving.