Unless they end up using that new mushroom leather that wears like real leather, I'm going to assume this new material is similar to alcantara which means it will collect stains, dirt, and smells very quickly and we won't be able to clean it at all. In my experience, eco-friendly almost always means "we wanted to save money with cheaper materials that will wear out faster while charging you the same or more, so we slapped a virtuous label on the crap"
I might be convinced that they truly believed in the environmentally friendly angle if Apple didn't change the design of each new iphone juuust enough starting with the 11 so that you have to buy new cases every year. Reusing accessories is far more environmentally friendly than buying new ones every year, even if they're made of virgin unicorn hair ethically sourced by fairly-compensated artisans. Either way I'll just keep up my tradition of not buying any Apple branded cases until they show up at TJMaxx and Marshall's for 70% off, but it would be really nice to be able to reuse our cases for several generations like we used to.