Materials don't just disappear from Shapeways. Ceramics is replaced with porcelain (although maybe the timing is not great). If your supplier doesn't deliver anymore, there aren't that many options. At least continuing is not one of them. I think Shapeways is doing a great job at trying new materials all the time. (although I might be a bit biased now since I'm currently an intern).
But if I would guess (really, just a guess, no intern knowledge or whetever) I would guess elasto plastic is a material to go. When it started I ordered a key sleeve in it. Now, after more than a year, I can say that I have never seen a material age so ugly. The material turned a dark grainy yellow. It's not a product material, more a prototype.
But to keep on topic: at Euromold I saw one of those objet printers from Stratasys with the multiple materials. The specs on internet look amazing. The models in real life were different. The different kind of materials do not attach that well to each other. Small details, like tekst or small layers could easily be pelled off. After a week of honderds of people touching all the models, the wear was visible. But one kind of model is still amazing, and that is the transparant soft material around the yellow hard material, making it possible to create a skeleton look in body part form. Things like this:
I held a foot, and it felt amazing. It felt like a real foot. And since the transparant material contains the skeleton, you cannot peal it off.