The idea of a combined municipality directly adjacent to Detroit is interesting. Are there other examples of this kind of binary system coming into existence elsewhere? It seems to run counter to the idea of core-city/edge-cities and exurbs.
As to the likelihood, I agree that the identities of some of the various candidates for inclusion are well invested in their own identities, and would be unlikely to want to take on such a revision. But then, there's nothing taken away from the character of various neighborhoods and communities in Detroit (or NYC, or Chicago, or...)