Continuing my series attempting to reconstruct how Babylon 5 was originally (for certain values of "original") "supposed to" go. More detailed explanation and Season 1 are here. However, since that original post I have acquired the actual treatment by JMS and am therefore working from that, rather than summaries. Thanks again to Glenn for giving it to me!
Although Babylon 5 was originally planned to end with defeat and
destruction of the station, JMS' plan was immediately to move into a
sequel series, essentially additional seasons under a new title, Babylon Prime.
Known: This series would open with Sinclair, Delenn, and their child in hiding, together with Garibaldi and a Narn ("a friend or relative of G'Kar"). They meet with the Grey Council-in-exile, who refuse to do anything to help Because Prophecy, and express the need for a base of operations. They go back in time and steal Babylon 4, but there are time distortions that cause problems. (Interestingly, even in this early stage B4 goes into the future relative to the date it's being sent to, then settles down in the correct date.)
This time travel would cause Sinclair, Delenn, and the baby to age very quickly, so the baby would actually be an adult for most of the series. Meanwhile, Londo would become Emperor and be implanted with a creature that spies on him and reports his activities to the Shadows. Londo captures Sinclair and Delenn, but then rebels against his not-actually-called-a-Keeper at unspecified "terrible personal cost" and frees them. Meanwhile, their son becomes "something greater than human."
Earth wins the second Earth-Minbari War and Sinclair's name is cleared. Babylon 4 takes part in a great battle that ends with the final conquest of the Shadows, and the victors form an interstellar alliance led by Sinclair and Delenn's son. Delenn leaves Sinclair to resume her position on the Grey Council and help her world heal. The series ends with Sinclair retiring to an uninhabited world and going fishing.
Speculation: The most likely place for Delenn and Sinclair to hide out is Epsilon III, where Draal can protect them. Likely additional candidates for their allies include Ivanova (if she survived the destruction of Babylon 5), Kosh (if he survived the end of the Shadow War), Draal, G'Kar and the Narn resistance, Talia/Lyta, and possibly Vir (though he is unmentioned in the treatment).
Some version of Talia/Lyta becoming a living telepathic doomsday weapon would likely have still occurred in this series, given that both Lyta's closeness with the Vorlons and Talia's telekinesis are set up in the pilot and Season 1, respectively.
In all likelihood, the "terrible personal cost" for Londo freeing Sinclair and Delenn is the same as in the broadcast series: his death at the hands of G'Kar.
Two things stand out as intriguing: Babylon 4 still swings into the future as a result of the time distortion, meaning that wasn't actually an obvious patch between a "Babylon Squared" that assumed it was being stolen to fight a war in the future and a "War Without End" that had it stolen to fight a war in the past. Also, Sinclair and Delenn's son being "greater than human" recalls Ironheart--it suggests perhaps that his role as spiritual leader who has odd powers and ultimately ends up leading a new alliance was ultimately divided between Sheridan and Lorien.
Frankly, while better than what we got of Crusade, this entire treatment is basically crap. With the sole exception of the Catherine Sakai as mole thing (which itself, recall, was speculation) none of this sounds likely to be as good as the series we got. It's much more straightforwardly about good against evil and the Shadow War, G'Kar's arc is jettisoned almost entirely, the Earth Civil War (which in my opinion was a better storyline than the Shadow War) is entirely gone, the ancient cycles of violence and "get the hell out of our galaxy" are gone, the massively powerful elder races whose technology is millions of years more advanced than the younger races are defeated in a war, Ewok-style, rather than persuaded to go away on moral grounds... this is simply not very good.
The timeline surrounding the theft of Babylon 4 is clearer and more sensible in this version, true. In "Babylon Squared," it's pretty heavily implied that the station is being pulled into the future. The retcon in "War Without End" requires that Draal first pull the station into its future so that passengers can be offloaded, then throw it into the past, which doesn't make a whole lot of sense. On the other hand, the treatment suggests an accidental trip into the future, so maybe that's what was going on in "Babylon Squared." On the other hand, the price of that sense is losing Sinclair-as-Valen and the reveal that all that Minbari prophecy is just him remembering the future. Which makes Sinclair Merlin, bringing in all the references to the Arthurian legend, of which there is no trace in the treatment. Plus, I love a good ontological "paradox." (As I have noted a few times on this site, it's only a paradox if you believe that information cannot be created ex nihilo. As someone who creates information of one kind for a living and of a couple of other kinds as my primary hobbies, I take rather a large amount of exception to such claims.)
It's notable, too, that this belies a number of claims by JMS regarding how closely he stuck to his original plans. For example, he has claimed that he knew what the last shot of the last episode of the series would be before Season 1 began. However, if he meant the end of the planned Babylon 5 series, then the shot of the station being destroyed while a single shuttle leaves occurs a few minutes before the end of the aired finale and in a very different context than originally planned (the actual final shot of the series, if credits are not included, is the sun rising over Minbar as Delenn reaches out for it; if the credits are included, it's a split screen of a young Londo as he appeared in the first season and the aging Emperor Londo seen in the flashforward in "War Without End.") If he meant the end of Babylon Prime, then there is no equivalent scene at all to Sinclair fishing.
There's also his claims in response to fan comments on the apparent contradiction between JMS' statement that after Babylon 5 finished he planned to stop writing for television and the announcement of the Crusade spinoff. JMS claimed that he had "always" said there was one possible spinoff idea he might explore given the chance, but that otherwise the end of Babylon 5 would be the end of the series, and indeed early on he did make claims that the series would consist of a planned five-year arc, possibly followed by a spinoff. Given this treatment, however, it seems clear that the spinoff he referred to in those early comments was Babylon Prime, and as such his citation of those comments in defense of Crusade is at the very least equivocation, if not outright prevarication.
None of this should be taken as a criticism of Babylon 5, nor is my point to suggest that JMS is a bad person or anything of the sort. Babylon 5 is truly great work, and JMS has done some other really great work in TV and comics (such as The Real Ghostbusters or the fantastic Rising Stars comic series). His scriptwriting textbook is excellent, as well. I am merely observing that some of JMS' statements regarding the series seem very likely to be deceptive statements with the aim of making it look more planned than it really was; as such, it calls into question his reliability as a source on the genesis and development of Babylon 5.
What we have here, ultimately, is a classic example of why at least the soft form of Death of the Author is necessary.