Puh-lease, we don't need another 50-50 tarmac-dirt track. It's an awful concept and we already have too much of it in the game.
I agree, however, that some kind of narrow country-side track would be a good thing, and I'm sure there are plenty of those all over the world to take ideas from. Really, I like SO, but after a while, the walls get annoying. For instance, the chicane in SO would be a much better corner if you actually saw where you were going. A blind corner-chicane? That's not only a lack of realism, it's just insanity if you're not on a league race.
I actually wonder what SO would look like if you just took the same circuit and put it in the middle of a field or something.