c. 16 BC Augusta Treverorum
genealogy of the plan for Washington DC
If reenactment as a design prescription is still only a "weak hypothesis," your consideration of the notion so far certainly contributes supplemental vitality and strength. I assume (and hope) you've read my paper for Belgium and my Tafuri critique before writing your reply, because my response here works along those lines.
The evocation of Serlio's 'street scenes' is indeed apt--the notion of stage set is very much part of reenactment, i.e., the place upon which and within which to 'act' again (and again). For the record, Serlio drew three scenes, the third, Scena Rustica or Scena Satirica, is all natural /naturalistic (proto primitive hut? or proto romanticism?).
While reenactment certainly necessitates a contextual understanding, reenactment as a design paradigm is nonetheless not necessarily site specific. For example, theme parks everywhere are for the most part far removed for the 'actual' themes they reenact. On the other hand, the reenactments within Venturi (Rauch) and Scott Brown's Franklin Court (Philadelphia), Western Plaza (Wash. D.C.) and Welcome Park (Philadelphia) relate directly to their respective sites/environments. Reenactment then can (and indeed does) have it both ways in terms of context.
As to the "problem" of "exciting ideas" never getting developed due to being brightly spotlighted and then quickly moved on form, perhaps this 'trendy' behavior too is a form of reenactment, that is, a repetitious renewal, the continual process of putting on a new hat, but always putting on a hat nevertheless.
The best philosophy I've read so far that purports reenactment is within Collingwood's The Idea of History. Collingwood is much influenced by Croce, and Croce is much influenced by Vico. [I have yet to do extensive reading regarding of the philosophy of history, but I have done enough to see that there is a significant strand of it that addresses reenactment as a methodology. I suspect Vico's New Science to be the most important primary source--I have the book, but have only read a small part of it so far.] When I first began to redraw Piranesi's Campo Marzio using CAD, I was doing so to get as close to Piranesi as possible; essentially, I was reenacting his act of drawing as best I could. For me, this exercise, this reenactment, has provided enormous insight, albeit it took several years of continual work for this vision to develop. I am certainly not Piranesi, nor do I contend to possess his superior creative talent and imagination, but I deliberately attempted to do some of the same things he has done, and in so doing I honestly believe I removed several degrees of separation. Perhaps reenactments then are always a play with degrees of separation, sometimes seeing how close one can get to the 'original' and/or sometimes seeing how far one can stretch the 'truth', to name the extreme cases. [play - theater - reenactment]
My historiography of Piranesi's Campo Marzio (and here I include my paper for Belgium with the work so far in the Encyclopedia Ichnographica) aims to present the Ichnographia as a prime exemplar of architectural and urban design as reenactment--Piranesi's plan is not only a large architecturally drawn plan, but also a plan in the sense that it lays out a course of action, or, should I say, a course of reenaction. Taking the lessons of the Ichnographia('s virtuality) and utilizing [reenacting!] them in today's world is the 'real' challenge.