We all already know that Ubuntu 17.10 and subsequent versions will have Gnome Shell as the default desktop, but it is true that at the moment there was no official Ubuntu image with Gnome Shell. Up to now. Finally and according to the development steps, Ubuntu already incorporates Gnome Shell as main desktop, with no option to choose between Gnome or Unity.
This arrival has been to the daily development images that are created daily, but we cannot say that the implementation is finished or that this is the general appearance of the desktop and the layout.
Gnome Shell is already in Ubuntu 17.10 but not Wayland
The first phase of development has been to use Gnome Shell as the main desktop, to which have used X.Org as the default graphical server. Later the Wayland graphical server will be used, but that will be when the rest of the desktop is more implemented. For those who want to use Wayland, there is an option in the repositories that will allow us to use this option. But you have to remember that it is not a stable version within a development version.
Unity 7 is still in the Ubuntu universe repositories, but there is no trace of him during the installation or in the first starts of the version. Being sad news for those who prefer to have a team with Unity 7.
Those who want to get this development version with Gnome Shell as the main desktop, you can get it from Ubuntu cdimage, a repository where the installation ISO images are uploaded, both the stable ones and the development images. However we recommend install on virtual machines since although Gnome Shell is a stable desktop, the version is not so stable and could cause serious problems on production machines.
I personally think that in this case, Unity 7 should continue as an official flavor, an alternative flavor as Ubuntu Gnome was born at the time, but it seems that no one has to do all that work Or maybe yes?