This question was raised on a recent blog post by Catherine Kavanaugh last week at Plastics News. It highlights my longstanding feelings about plastic (or any other material) being used as a substitute for another material, namely that there are.
"...two diverging paths for the industry. One would be to build a system of components that are so good that they’re indiscernible from wood siding and trim at arm’s length. The other is to build a system of cladding that makes no attempt to fake wood, but rather celebrates the fact that it is vinyl."
I've always felt this way about other products, such as vegetarian food. Many omnivores (including me) look askance at something that is a vegetarian knockoff of a meat-containing dish. Yet dishes that don't contain meat and don't pretend to be meat are commonly consumed without question. Nobody complains that fettuccine Alfredo is vegetarian, and that is because it doesn't pretend to be a meat-substitute. But vegetarian hot dogs? Not a chance. The fettuccine celebrates the inherent qualities of being vegetarian while the mock hot dog only mocks it.
So what are the inherent properties of vinyl that we can celebrate? (Unfortunately, Catherine's blog has not yet had a single comment). To me, one of the key characteristics of vinyl or (any other plastic) is that it is plastic in the traditional definition, meaning moldable. Plastic can be easily formed into three dimensional shapes that wood, stone and brick can't. Take advantage of that and do so in a way that allows it to excel in any of the demands placed on siding (weatherability, water/hail/snow-repellency, insulation, visual appeal).
I don't have any specific proposals, but that would be how I would tackle the problem. Call it the fettuccine approach. The vegie dog approach has already been tried and we know the results. Not good (or we wouldn't be having this conversation).