I'm sure there are many ways to assess the maturation of a mode of inquiry from scientific fad to scientific field. One marker is the building of a fad onto another fad. So emergence could be viewed to have progressed from fad to field when someone writes a book relating emergence to East Asian philosophical/religious thought (something like the Tao of Physics or others). Once fads begin coalescing around a scientific mode of inquiry, that mode of inquiry is being legitimated into an accepted field of science. Thomas Kuhn, in his Structures of Scientific Revolution, failed to entirely grasp the legitimation process, outside of scientific rationale itself, that contemporary scientific fads must undergo (it requires more than the acceptance of the Church - not that Kuhn was suggested this). While parts of the above are written a bit in jest, I am serious about the importance of scientific paradigm legitimacy. For new theories, the legitimation process is fairly simple (journals, research funding, ...). For a paradigm (or more humbly, an entirely novel perspective) to gain ground and progress from "crackpot" fad to something greater - there must be social acceptance, underlying scientific support and rationale, and other more subtle factors. Viewed as simply a scientific perspective in a history of scientific inquiry, an objective rendering of the evolution and contemporary significance of emergence would be quite interesting to read.