This will be possible.
The most popular GNOME Shell extension is system tray icons support. The GNOME developers have removed the legacy tray support, but end users are suffering.
Good thing we collected data on extension downloads so that we’re able to know what is the most popular extension, eh? 
Status notifier support is actually on my to-do list due to the high number of requests for this feature, although our initial designs do not involve a tray, but a less-prominent menu structure. Help welcome, because it’s not at the top of my to-do list. Ticket here.