There are many reasons to shoot digital but the fear that film will not be available in the future is not one of them. Unless we all stopped shooting film for that very reason. I would not be surprised if many of the modern devices and supplies will not be around in the future either. Film is still here so if you want to use it do so. I cannot see SD cards being common twenty years ago so why buy a DSLR that uses them? Other than you can use them now and for the forseeable future. As long as enough of us still enjoy shooting film and keep buying it some one will still make it for us. Will enough young people also use film to replace us as we fade away, that is another question but it will be answered not in the next 3 to 5 years but at least a decade longer I believe.