Personally, I would like to see NautilusView die in favor of using a
BonoboControl with a defined interface API for Nautilus embedding.
Things that didn't follow the defined API would not get progress shown
with the throbber, and various other little things. Though, I doubt
that anything like this will happen. :-/
NautilusView is what you describe. It is a bonobo control, with a defined interface for doing the extra stuff needed (like the throbber, navigation, etc). When you embed a regular bonobo control in nautilus that also implements PersistFile or something (like eog), you don't get the throbber stuff (IIRC). How is what you want different from this?