Good analysis. It's worth noting that The Original Series (as we know it), really only fleshed out two time periods: The late 20th century (because that's what the writers knew), and the time period immediately preceding the Series.

There's a huge gap of time between present day and TOS that' has slowly been filled in by subsequent Series and movies, eventually culminating in Enterprise. On the other side of TOS, there's a large time between it and TNG that's largely unexplored.

Good article.