I doubt anyone really believes that today's DRM will be any impediment to copying software 100 years from now. The problem is that DRM by its nature doesn't distinguish between uses that should be prevented by law anyway and legal uses that are only disrupted by the technology. If those anti-circumvention provisions you mentioned were abolished, that would be much less of a problem in practice.
That still leaves all the other questions about the duration of copyright protections, what fair use or the equivalent concepts should mean in an era of technological protections, and whether it's healthy for society to encourage perpetual rental models for creative work rather than permanent rights to access any given material, but these are separate (and potentially complicated) debates to be had.
That still leaves all the other questions about the duration of copyright protections, what fair use or the equivalent concepts should mean in an era of technological protections, and whether it's healthy for society to encourage perpetual rental models for creative work rather than permanent rights to access any given material, but these are separate (and potentially complicated) debates to be had.