Yeah, you're right about the story being predictable if the series is redone word for word. But that wouldn't be a true remake. A true remake would be, yes, an updated version of that story but to make the story more of its own entity too, the characters would have to be altered in some ways that wouldn't be too fundamental like Starbuck being turned into a woman yet keeping the same cocky, maverick attitude as the original Starbuck.
And some new plot twists would have to put in the story to give some unpredictability like in the sequel to the original Battlestar Galactica (Galactica 1980), the fleet reaches Earth they've been looking for only it was the planet of that present. But in the NuBSG, when the fleet reaches the Earth they've been looking for, it turns out to be a nuked wasteland. It wasn't until the end of the series that they reach our Earth, which wasn't that of our present but of our prehistoric past.
And you're right about how hard it would be to do 100 hours of TV for this show and to get a group of writers willing to do it. But if I were to do a Babylon 5 remake, each season wouldn't be 22 episodes long. Each season would be 13 episodes long. Less filler yet some space for a few non-arc episodes.