I've been wondering about this for the longest time. As an SKU fan who sees the movie as a grand finale, I'm always making up theories about where the characters go after all this is over. And no, I don't mean like what their real life jobs would be. I mean, within the general cosmology of the Utena-verse, what do you think happens after Anthy and Utena ride off into the sunset?

My theory: Ikuhara was writing the anime Paradise Lost. It seems obvious that the genesis of Ohtori Academy is inextricably linked with the fall of Dios. From what we can infer about the world of Dios, it appears that he and Anthy lived in a world of fairy tales. Perhaps there were many heroes before Dios, but none of them ever fulfilled the role so well. Proto-Juris, Proto-Saionjis, these heroes had manifold adventures, but were never so masochistically pure as to be able to make "all the girls in the world princesses". Dios steps in, a concentrated jolt of pure self-sacrificing heroism. Dios instantly makes all past heroes obsolete. Dios is like the disney versions of old fairy tales, Campbell's condensed feel-good story. But by perfecting the childish, feel-good nature of the fairy tales, Disney bleached the genre and turned it into a cracking, crumbling pillar of the old order. So goes with Dios. Eventually, Dios breaks down, world gets pissed, Anthy gets skewered. Dios, nearing the brink, thinks first a parallel universe perhaps could be the perfect scene.

Thus, Akio. Dios lets all of his buried wickedness come forth. But Akio is not a a stable creature. The trauma of the world's rejection of him (and the world's subsequent collapse/destruction) have scarred him forever. Noe the doomed master of the parallel world of illusions known as Ohtori, Akio sets out to soothe his fears. How does he do it? Like any good neurotic, with obsessive repitition! The world of Ohtori is in a cycle. New people are born. New heroes are born within this group of people. Akio ensnares heroes in some form of contest (as Mikage's story shows, it wasn't always duels. The only factor that had to stay the same was a struggle for eternity/revolution/miracles). Akio already knows who among them is the most princelike. Then to prove that evil always triumph because goodness is false (since how anyone ever be better than Dios, and Dios fell!), Akio works aggressively to first make that prince all he/she can be, and then smash her/him down in a fit of psychotic rage. It's like The Matrix-Neo's prgrammed into the system.

But then Akio runs into the same problem as the Nazis in The Great Escape. By cultivating and bringing together the world's (Ohtori's) greatest heroes, Akio leaves himself open for them becoming even greater than he used to be. Utena does this, becoming an ubermensch who synthesizes the virtue of Dios and the passion of humanity into a new heroic ideal. Utena gets skewered, Anthy ditches Akio.

Anthy, in her search for Utena, realizes that the world of Ohtori is now hers to command. She makes severe changes, castrating Akio's cocktower and turning the dueling arena into her new rose garden. Also, there is a plurality of spires in this 'verse. this symbolizes the new plurality of heroes. Juri, Miki, Saionji, Kozue, everyone else except Touga and Nanami survived the fall of Akio nad now live in the new Ohtori. They are brighter, better people, more forthright and more true to themselves. Touga and Nanami could not progress for one of two reasons:

either: a)Nanami and Touga both were too evil in the old Ohtori, and thus are only seen in Mohtori as ghosts, a la Makio.
or: b) Ikuhara always wanted to kill Tuxedo Mask off. Touga, being this series' heterosexual love interest for the female protagonist, gets shafted due to ikuhara's overzealous love for yuri. Nanami gets turned into a cow so she can serve the same role she did in the series: comic relief filler.

Although option b seems the saner choice, I'll subscribe to option A for the purposes of this essay. So Anthy hooks up with Utena, who is angsting over that eternal question: so was Series!Touga just a dick, or what? Realizing that he was a truely noble soul (makes you wonder why he didn't get to, you know, live). The story of the girl in the boat? That was both Utena AND Juri in the boat. Watching the series, it quickly becomes clear that Ruka is really just Touga with blue hair and a british accent.  Both sacrifice their own purity in a desperate attempt to save the girl they love. Touga explicitly states that the only reason he lets Akio assrape him is because he believes Akio is noble and can teach him the methods by which he can save Utena. Like Anthy, a belief in Akio as a good guy damns him. And by sacrificing his purity, Toruka brought abouthis own death without actually helping anyone.

Back on topic: So Utena and Anthy ditch Ohtori. Anthy drives Utena through Gacktio's roving castle-o-death and officially earns her Action Girl license. They kill the prince, and go off to the outside world...

AND BECOME THE ANIME!ADAM AND EVE!!!!

This is just speculation, but look at this final passage in Milton's Paradise Lost:

"To the subjected Plains; then disappeared.
They looking back, all th' Eastern side beheld
Of Paradise, so late Their happier seat,
Waved over by that flaming Brand, the Gate
With dreadful Faces thronged and firey Arms:
Som natural tears they draped, but wiped them soon;
The World was all before them, where to choose
Their place of rest, and Providence Their guide:
They hand in hand with wadding steps and slow,
Through Eden took Their solitaire way."

This sounds a lot like the end of Adolescence Apocalypse, at least to a classic lit manwhore like myself. Not biologically possible, you say? Juri said they ALL would reach the outside world some day. So the students of Ohtori all leave and repopulate the barren Earth. Our heroes form guild's, teaching nw generations the essential arts of fencing, piano-playing, etc. I generally like to imagine that the personalities of the PostOhtori Student Council members being some what along the lines of Richard Henry Lee from 1776, a bunch of amiable blowhards with surprising talents.

Now what's left up to debate is just who pairs with whom. My money's on:

Utena-Anthy (Duh! Though they may recruit Miki for sperm services)
Juri-Miki (They definitely had a newfound chemistry in the movie)
Saionji-Wakaba (Unfortunately Tatsuya, Utena's is the only pussy Wakaba is fond of)
Tatsuya-Kanae (Their perfect for each other, in a weak, pushover kind of way)
Shiori-Kozue (1. Because they fucking lived, goddamit, and 2. Cause why the hell not?)

These descendents go on to have all the other adventure documented in anime. (That last theory is total crack, but what explains Nina Einstein's bitchy, table-humpingly horny antics better than saying she's a direct descendent of Saionji?)