I think I always suspected that there would be more to the Londo and G'Kar story than that simple choking flashforward was telling us. Like, if JMS was spoiling that so early on in the show, there had to be a reason, had to be more to come.

I thought there had to be more to it, too, for that reason, but my guess was that either Londo's vision was symbolic rather than factual, or (as we didn't know yet how this show handled prophecies and time travel and timelines) it was a warning for a future event which could be prevented.