Leather and leather by-products can be recycled
Leather trimmings from the manufacturing process can be repurposed as stuffing, (into boxing punch bags for example) or combined with other materials to make composite products such as leatherboard, which is used for insoles and heel inserts in footwear.
Leather at end of life can be ground down to use in this way too. At the very end of its life leather will biodegrade, depending on type in between 10 & 50 years. We see leather trims being creatively incorporated into wall coverings, plus more and more companies are recycling the leather component from footwear and leathergoods into something new.. Read the Peterson & Stoop article.