Although I would be very saddened by all the aircraft that will get grounded by a 100LL ban, I do welcome the fact that if nothing else, it will pull the aircraft industry kicking and screaming into the modern world.
It's nuts that they haven't come up with engines that can run on unleaded or explored diesels. The Germans managed to certify not only one, but two diesel engines in a couple of years (the Austro in record time) and Continental and Lycoming are still scratching their a**es? Continental has now bought a french diesel, so let's see where that goes...