Icons needed: Screen cast & remote desktop
Recently GNOME Shell has gained support for providing screen casting and remote desktop support. Under Wayland it's in complete control of screen cast and remote desktop sessions, while still allowing both sandboxed and non-sandboxed applications to use said feature.
As described in https://wiki.gnome.org/Design/OS/SystemStatus it'd make sense to have the state related to screen casting and remote desktop available to the user to be inspected and managed, and for that icons are needed.
Either two icons; one for screen casting, and one for remote desktop (i.e. most likely screen cast + remote control), or something that covers both.
Besides this an indication, the top-right menu should probably also give the user an option to "Terminate" a sessions, but for that no extra icon is needed.