According to a Google search of class-central about 4000 Coursera courses match the "may be unavailable" distinction. These are generally any class that was ni

According to a Google search of class-central about 4000 Coursera courses match the "may be unavailable" distinction. These are generally any class that was niche and traditionally taught. I.e. a philosophy class that covers prolog. Classes that are alive since ~2015 or earlier are usually remade every year or two to be more like a video introduction and are in a theme of either universal interest or that is mandatory for a particular degree (the first being good for bringing in new users and the second being good for certificate income.)