If it is for strengthen the marketing, I think (at least at this point in time) that the better would be focusing in making Fedora "that 'linux' where everything works and I can do my stuff", and, after, "that really cool computer system where I can do really cool stuff".

If it is for a instantly recognizable visual identity, then you inevitably stay hostage of the thing that draws things on the screen (GNOME Shell, for Fedora Workstation). The only way around is to put a logo in the face of the user (GNOME Shell's top bar, because the Wallpaper can easily - and will - be changed).

So, my suggestion to this topic would be:

1- Keep (really) focusing (harder) on making Fedora "doesn't suck".

2- Put a (symbolic, 1 color) Fedora logo somewhere in the GNOME Shell's top bar (like macOS, like Windows 10's bottom bar, like Ubuntu's left bar, [...]).

3- Remove logo from default wallpaper.