I don't think anyone has answered my question on why no new twin designs have come to the market for such a long time. The liability issue can't be extra bad on twins over singles.
Is it because high perf singles come so close to the perf of a twin that most people buy a single, and only a small % of buyers are willing to pay the substantial premium (fuel and maintenance especially) for the engine and systems redundancy? And those buyers are happy to just keep maintaining an older aircraft?
Having said that, there are very few "new" 150kt+ single designs...