It would be interesting if they tried a different approach, such as the selling of a required proprietary part of Carrara, and making the rest open-source. In this way they could make the source code public, and folks can contribute, but they would maintain a core required piece that they could sell. That way the public could contribute, and they could maintain a product.

Although...I think the market in this space is probably too competitive, and those who would benefit the product probably would prefer to focus on improving more fully open-source and powerful products, such as Blender.

If they just released it as open source, they would basically be releasing what could develop into a competitive product, as the public would not be able to maintain support for the proprietary figures and technology that they put into their other products. So there is no benefit to them as a business to do this.

The outlook has not looked good for a while now...the longer it goes, its a pretty safe bet to assume it's been shelved.

IMO, Poser is the most similar software, though not cheap, but other than modelling has a fair amount of similar features, and is built to use all the same content, just as easy...except for the newer Daz stuff. I don't even use it now, but am saving up for it for the next sale, as I would like to try its newest toon and drawing style features, and have again access to its animation set and dynamics. (some may argue Blender or others, but nothing but Carrara. Poser and DS were made to use the content so easily, imo)