@Knixon said:

Had picked the Narn to align with, rather than the Centauri?

Seems to me it's quite possible that the death and destruction would have been far worse, and the Centauri may have actually been entirely eliminated.

In that light, it's possible that the Shadows would have "won" and there would be another 1,000 year or more cycle begun before they came around and knocked over all the anthills again.

The Shadows would have lost in both cases. The Narn are headstrong, but too limited in 'what they want'. They would burn out when they have eradicated the Centauri, and become useless for the Shadows. The Centauri want to regain their status, but are 'too weak and divided' to do this without the aid of the Shadows. It was a miscalculation of the Shadows to think that they were in control and could use the Centauri for their nefarious purposes. In the end they payed for underestimating the 'madness' of Londo opposing them.

Well yes, in terms of overall galactic conquest etc, the Shadows made "the right choice." But I do think that if they had picked the Narn - by mistake, as it were - the Centauri might very well have been wiped out, although the Centauri didn't do that to the Narn or anyone else.