I love inline 6 (not V-6) engines and inspite of the fact that they are very long, I can't stop craving for a motorcycle with one. I keep poring over pictures of the Benellie Sei, the Honda CBX, and the Kawasaki Z1300. Maybe I should really look into buying a Z1300 or a CBX. I found a Benelli 900 Sei that was sitting in a museum in New Zealand with less than 100 miles on it. The museum was liquidating and they wanted US$15k for it. I didn't have the money then. Oh woe is me.....
Anyway, Ducati will never go with a straight six simple because it would be an aerodynamic disaster. They could do a V6 but I am pretty sure they won't. A V-8 ducati would be really cool, and so would a V-10. If they go racing with a V8 or a V10 and make a street version, I'm buying. Overall though, an 8 is much more likely than a 10. a 5 cyl wide engine is narrower than a straight 6 but its still pretty wide.
But back to my inline six fantasies, I start to think that while this sort of engine is not the optimal choice for lap times and aerodynamics and thus not suited to hard core sportbikes, on a naked bike ( like the ZRX or the FZ1), where there is space for considerations of character and alternative thinking, methinks a large capacity inline 6 would make for a very charismatic motorcycle.