Your deffinition of Undeath is pretty much the same as mine.
The only “detail” that I found interresting, that could be found in … teaching as well as in the Green Order stuff, is the hability to use the Undead masters as an “anchor” to prevent the second death. This is what makes the difference, at least in my mind, beetwen the path of progressive transformation (using regular communion, feeding , and exercice), and the method called “the path of the Dragon” in my book, that imply a form of possession.
What you describe is a common problem with Magickal organisations. I saw many of them rise and collaps due to members going their own ways. In the Left Hand Path, we are generally striving for personnal goals, and this make long term association difficult.
Time are also evolving. In the time of my mentors, people did not possesse cell phones, PDF books, emails and computers. Belonging to a secret society was really something. You received knowledge you could find nowhere else. Today, you can learn find more text in a week than adepts of the past could in years, just by purchasing books on amazon. Occultists of the previous generation sometimes waited for years before having the opportunity to meet a famous magician and exchange few words after a group ritual. Today, you can easily talk with an author such as E.A.
What makes the difference now, is our personnal discipline; In a world where everything can be find, focusing your attention to only one goal, instead of jumping from an information to another, as become the new challenge.
In this context, I don’t really know what kind of future exist for “orders” and “lodges”.