Yup, many reviewers called it ugly (although I liked it better than the E-1 design). There are even some E-300 users who insult their own camera by calling it the Ghettocam.Personally I think the E300 was built better than it was supposed to be, with all the trimmings like vertical grip, cable release and underwater housings.
Perhaps the poor reception to the radical body shape was what killed the design.
I wouldn't hold my breath if I were you. With the introduction of E-400 I think it is quite clear. I think flipping the mirror upwards instead of sideways is easier and more reliable. It is not just about body design and matter of taste, traditional mirror chamber and movement is a pure mechanical solution that is simple, reliable and works by itself most of teh time for most of the photos, since they are taken in horizontal (landscape) position. I think that makes camera design easier. The other fact is, to have two different factory routines is expensive. I think we should face the fact that the E-3xx design was just an odd one. Is there actually any advantages with the design other than opening up a market to people who like the shape?... waiting for E-360 or something.