Very interesting article bout the Orenda V8, when it came out I was hopeful about the engine but my fears were realised, it simply weighed too much.
But it does appear the cabin class piston twin is dead. Yes there are plenty of old airframes out there, but they are getting older and older. Even the Lock and Key Chieftains from Mike Jones Aiircraft while beautiful, are still at least 25 years old.
At present, you simply cant buy a new cabin class piston twin.
Interesting article on aerodiesels
http://bmepinc.com/AEHS%20presentati...%2005%2008.pdf