To drag this back up again have we had any comment from JMS since on what the original plan was?
That Kosh has the recording of Talia does seem like a clear hint to me that the real "trapdoor" with Talia wasn't activating the control personality but rather not bringing her back afterwards, I wouldn't be surprised if this was a similar kind of trap door for a lot of characters.
What form would the "brining her back" take though? Just having Kosh use the recording to bring her back at once seems a little too easy to me. Maybe as was mentioned (much)earlier if Talia was intended to largely follow Lyta's story the recording could have replaced Lyta's being enhanced by the Vorlons? perhaps the sleeper Talia is handed over to Kosh or the Vorlons get hold of her(similar to say how they kill Deathwalker but taking her transport instead) before she can return to the Corps?
Perhaps the way Lyta was used after this point might suggest when JMS might have put the control plot into use? she returns early in season 3 but doesn't become an important character until close to the end of that season. I would guess that with an established character like Talia JMS would not look for a break to be that long, maybe a few episodes but not an entire season.
The control personality does seem like it would be a good fit for the events building up to B5 declaring independence, After that point you could say it would lose some of its significance since the heroes anti Clark plans would be more out in the open, even if she'd then found out that Ivanova was a Telepath Bester and co that in itself wouldn't be as dangerous to her immediate future. A few episodes break of that would bring Talia back into the plot around the point Lyta starts to become important, maybe never linked to Kosh but arriving with Ulkesh?
Erm, no. Speak for yourself.
Well I'll speak for myself- it would have been freakin' awesome. This not happening is the biggest reason the first half of season 5 is weaker.
Let's get over our Byron hatred long enough to imagine the story of Ivanova falling for Byron as a proxy for Markas, then having to go through the torturous emotional and ethical quandary of having to choose between him and Sheridan, deciding to do her duty and take out the telepaths, thus finally shutting her heart out to love and happiness while truly completing her despair over Markas.
Ivanova was set up from day 1 to be a tragic character, like Londo, but on a smaller scale, though equally heart-breaking. And that vision was never realized.
A few years delayed response but I can't say I'v ever really seen Byron as a natural progression for the Ivanova characters plot, I can definitely see
how she could have been used in such a fashion (although I'd guess a different Byron casting/performance might have been needed) but to me it seems like a regression. Surely the point of her earlier tragic nature was to get her to close off to Markus and then have the equally tragic lesson similar to Sheridan that you need to engage emotionally with people not just be willing to die for them(Lorien makes the point to both of them). Having her open up to Byron but then have the situation go south again seems like a direct counter to that lesson.
Interesting to consider what JMS might have done with Talia/Ivanova if the former had stayed in this regard. Perhaps the relationship might have lasted longer or perhaps stayed as a friendship and only gotten romantic just before the control personality was used Talia's if JMS wasn't able to get a same sex relationship that much screen time. More potential to show Ivanova committed to it maybe revealing she's a Telepath to Talia but perhaps not as much of a kick at the end of it? rather than having Talia effectively killed for good perhaps having the relationship ending as a product of a lack of the control personality or maybe Talia losing memories of it considering the recording was made in season 1.
Perhaps its too far in advance to really know for sure but I wonder if the Byron/Telepath plot would even have existed if Talia had remained, to me a lot of its purpose seemed to be to give Lyta a reason to have a more direct vendetta against the Psi Corps which Talia would already have with her history. I spose you could argue that Talia would naturally work in the role Lyta plays there with Byron being rather similar to Ironheart and her previous links with the underground railroad but I don't think it would provide previously missing motivation. JMS would have had less time after the earth civil war in the original plan as well given that it would have only been concluded in season 5, maybe it gets dragged out of much of the first half of the season and then links into the Centruari conflict building towards the end of the season?