With the end of Ubuntu GNOME and the adoption of GNOME by the standard Ubuntu, will Ubuntu GNOME 16.04 upgrade to the standard Ubuntu 18.04?
Yes, by default it will. Please see the release notes. There you can also see that it's easy to keep using a desktop closer to vanilla GNOME, if you like, by installing
vanilla-gnome-desktop, then choose GNOME on the login screen.