Writing a convincing script

The idea of writing a script for the third film in the Chinatown trilogy(as it was intended to be at conception) has been lingering in my mind for quite a while. The first two pictures-Chinatown and The Two Jakes,respectively-did a remarkable job of showing the evolution of Los Angeles. Chinatown was conspiratorial about water in the 1930's, while the Two Jakes concerned itself with Oil and Real Estate(Jews and WASPS,respectively).
More important than the traditional and historical significance of the films is the way they tap into the psychology of the times. In The Two Jakes, one gets the impression that Gittes wants more than anything to forget his past and to aclimate himself to the growing speed of life in LA. Towne suggests that this was quite impossible because while many of the citizens looked at postwar LA through a new lens, the mechanisms of the city were more or less the same as they were before the war(the events which unfold in The Two Jakes are resoundingly similar to those in Chinatown).
The problem in penning a script for a third film in this trilogy is that it has become increasingly difficult to identify modern attitudes towards life in America. The third film would take place around the end of Gittes' life(mid 1960's when the no-fault divorce rule was introduced). But while The Two Jakes had the advantage of being set in a period with an identifiable outlook on life(the postwar optimism of the 40's), the third film would have to contend with many of the social disorders of the time. Thus the film probably wouldn't have the same center of gravity as its predecessors, and this makes me think the whole thing is worthless especially given the low attention span of modern audiences.
Back to Riemannian Geometry for now....