I think that's one of those things there was just never time of budget to do in the show since they had to ramp up again introducing the new captain. Sakai's fate is mostly covered in the novel "To Dream in the City of Sorrows" by Kathryn Drennan (at the time, Mrs. JMS). I highly recommend it.The reason why JMS decided to make the change was in large part because hanging both the Minbari connection *and* the Shadow connection on Sinclair would simply have stretched the realms of possibility. He's said repeatedly that Anna and Sakai couldn't have fulfilled the same functions.
That's interesting. But then what WAS Sakai's purpose? I was mildly annoyed that they put her in peril in a plot completely unrelated to Sinclair and started to build up a relationship with G'Kar but as soon as Sinclair exited stage left she vanished as if she no longer had a purpose? It looked to me that they had been sowing the seeds for the Anna Sheriden plot and just dumped Sakai when she could no longer fulfill that role. I would have preferred it if she had been given one final guest appearance to complete her personal arc even if her ultimate fate remained unknown.
Jan