"Ready?" "Why do your people always ask if someone is ready right before you're going to do something massively unwise?" "Tradition."
REVIEW: This is all gets rather Moffat-era Doctor Who, which is its own kind of exciting. It's all circular, with the characters acting on information they're potentially getting from future versions of themselves speaking to them from the past. Marcus' Merlin theory aside, this is like the source of Kosh's prophetic knowledge, although he did seem attuned to possible changes in established "history". The power of prophecy does exist in the B5 universe, but since temporal anomalies do too, and transmissions can be broadcast through them (like B5's distress signal 8 days hence), seers might be getting telepathic visions from those holes in space-time. But I digress because time travel is a hobby of mine. The point is, this two-parter will finally(?) show us the events of Babylon Squared from the other side, while also explaining how Babylon 4 was instrumental in saving the universe from the Shadows 1000 years ago, AND spinning Sheridan off into a dark alternate future that presents the stakes (why they must save the cheerleader) and gives us interesting variants of tried and true characters.
Of course, the big thing here is the return of Jeffrey Sinclair. He's required to bring Babylon Squared full circle, but because the actor has been out of commission, the production needs to cheat B-Squared's projections. Sinclair has an unexplained scar to match his appearance in that episode, for example. One imagines it would have been an onscreen event if O'Hare had stayed on, and been a revelatory moment inching us closer to the closed loop (and would that loop have closed later?). But then, the "memory" of him and Garibaldi in a hellish firefight also seems suspect unless they can get Sinclair to B5+8d, so yes, fine, the timeline is in flux. Babylon Squared might have made certain events more likely, but paradoxes be damned, they're not set in stone. That firefight won't happen if the heroes win, and neither will that destruction of the station. We can already see time-tweaks, like different hair and clothes from those showcased in B-Squared (nitpicks easily explained away). And if even previously experienced future moments aren't sacred, it means the Shadows CAN succeed in their plan to change history. They would avoid the paradox by going into dormancy anyway, but having lost fewer ships, they would be stronger in the present. Works for me!
That possible future with stronger Shadows will have the station destroyed within 8 days, but if the farther future Sheridan visits is part of the same timeline, he'll have escaped that destruction and won the war against the Shadows eventually. Or so Emperor Londo tells us. He now wants revenge because though an Earth-Minbari (and whoever else) alliance won the day, Shadowy remnants still remained and laid waste to Centauri Prime. Since this would have been a case of "you reap what you sow", it could also be the Republic's fate in the true timeline. The Centauri certainly deserve it. Shunting Sheridan out of time is actually a good way to keep him in the hero's role while also giving Sinclair his due. The latter's character has obviously changed, or else you couldn't buy into Marcus' contention that "Ranger One" is super-cryptic (the Sinclair we knew was as much a victim as Sheridan is of being surrounded by cryptic wise men and women), but the old spark is still there. I hope O'Hare is having fun for real, because it looks like Sinclair is, playing action hero after years of contemplative ambassadorship and training others to be action heroes. Poor Garibaldi is missing all of it, his best friend at least leaving him voicemail. It all has the makings of a PROPER send-off for Sinclair, both epic and personal. Part 2, here we come.
ON THE OTHER SIDE OF THE WORMHOLE: Trek became notorious for time travel shenanigans like this, the past and future collision most reminiscent, at that point, of TNG's finale, All Good Things...
REWATCHABILITY: Medium-High - At times, you can see the seams as the Sinclair situation is rewritten to adapt to real-life events, but it's all coming together rather nicely nonetheless.