Ubuntu Desktop Team had a recent meeting where they decided that Ubuntu 17.10 will have GNOME as the default desktop session.
The switch will be made from Ubuntu 17.10 Alpha 2. The first goal of the desktop team is to make a smooth transition to vanilla GNOME and later they will decide whether to include any customizations or not. They are also considering a complete switch to Wayland.
The decision make sense as next LTS is just a year away and it is pretty important to have a rock solid base by then.
Unity 7 will be available in 17.10 repos if users prefer that instead of GNOME.