The (modern Western) definition of "religion" is corollary to the fragmentation of human activity and knowledge into an ever-increasing number of separate fields. Since Antiquity "religion" has defined itself in both an ever more precise and narrow way against politics, war, sports, philosophy, science, arts, technology, medicine, psychology, etc. We can conclude that religion has lost ground, but it has been actually defined as "something else" than more and more "other things". A number of situations that would have drawn people to church/temple/mosque/synagogue now lead them to their doctor, therapist, teacher, library, museum, etc. But "religion" still exists (ek-sists, as distinct from the rest) because the other fields do not (and imo cannot) address or cover all the space of human experience. At some point of its reduction it may prove irreducible.
Now what kind of "religion" will survive or develop, and how extant religious traditions and institutions will fare in the process, is a very different matter.