I just finished my second viewing of the second season of Voltron, so I has some hypotheses going on in my head. Granted, all but one of them are probably pretty f-ing obvious.
1: Alfor was the former Paladin of the Blue Lion
I think that King Alfor was likely the previous Blue Paladin. While I think it wasn't exactly mentioned in the series, the website mentions that the Blue Lion is the friendliest of all Lions. This is probably the aspect of it that made Lance the natural choice out of the current Voltron force to be it's pilot. In a way it makes a lot of sense. Lance does seem to be willing to give people the benefit of the doubt, often for the wrong reasons, and also to his own downfall, but I think there's a certain gentleness and care to Lance that makes him a good choice.
But I think Alfor is an even better choice. From what we've seen of Alfor, he's been nothing but caring and considerate and very clearly left a positive impression on Coran and Allura. About the only person we've seen that he was close to that didn't think well of him in the end was Zarkon, but that wouldn't mean very much because Zarkon fits very snugly into the "Worst than Hitler" category. And I think this all works out my next point, which is where I go into the obvious territory.
2: Allura will be the Blue Lion Paladin.
If you know anything about the classic series, this is expected, and with Shiro gone, this is probably how it will go. It would make some sense with her being the pilot of the blue lion if her father was. She is his successor and she very clearly tries to live up to his standard, but as this series shows, while some of it is natural she holds a lot of prejudices which I'm sure will hamper her ability to bond with Blue in the first episode she tries.
Allura is very clearly a bigot, and she's made no secret about it. Even going so far as to give Keith the cold shoulder when she found out he was part Galra. But what would make this meaningful for her character is this may require her to confront her demons. This wouldn't at all be something new to the character. Her distrust of all Galra has been something she has fought against when dealing with the Blade of Marmora. This would give the show more opportunity to address that as she learns to master the Blue Lion.
But once she finally gets past it, the qualities of her dad that she shares will be more apparent I think, and this could bring a peace to the character. And really, even with her problems she would probably make a better choice than Lance because...
3: Lance will be the Red Paladin.
Just like I think Allura eventually being blue makes sense, I think Lance being the next Red Paladin is perfect. Like the Red Lion, Keith was hot headed and instinctual in regards to how he handled things. Even up until the end of season 2, he would leap into risky situations because he thought they were the best at the time and he didn't question it. Keith was a perfect choice for the Red Lion, but so is Lance. Lance initially was shown to have a pretty heated rivalry with Keith, and while things have improved between them, I'm not sure that's all gone away. Lance isn't necessarily as hot headed at Keith, but he certainly can be. But what makes Lance a good fit for the Red Lion probably isn't his hot bloodedness, but his overconfidence. He's every bit as likely as Keith is to plunge head first into danger with really no thought of the consequences until it's too late.
Out of all the pilot changes, I think Lance's will come the most naturally and he'll master the Red Lion fairly quickly. Which will probably cause him to gloat, and might eventually put him in danger as a consequence.
4: Keith will be the Black Paladin.
Season 2 spent plenty of time building up to Keith replacing Shiro as the Black Paladin. While I don't expect he pulled a Golion Shirogane and died, or a Voltron Sven and got sent to the Hospital Planet, I do think Shiro is going to be... mostly removed from piloting Voltron. I'm not ruling him out of it, but I expect he'll play a different role in the future with Allura as an active pilot, but I don't see him ever piloting any lion but the Black Lion. Being leader is something Shiro is really good at, so much so that I think the Black Lion is the only one he can bond with.
What makes Keith different from Allura and Lance is, I honestly don't think he's going to be a good enough fit for the Black Lion. At least not at first. When he piloted the Black Lion at the beginning of Season 2, it was acting to help save it's Paladin. Rather than it letting Keith be it's pilot because of his abilities as a leader, it was helping Keith with their mutual goal. But it's possible it saw something in Keith that helped it decide to let him pilot it. And Shiro seemed to see it too.
I see Keith's story in season 3 to be somewhat similar to Zuko's in Avatar. Granted Zuko didn't suddenly become a leader, he had to try to take what he learned from his uncle and apply it, and that's probably what Keith is going to do with what he's learned during his time with Shiro. And like Zuko, he's probably going to have no confidence in himself. This much seems evident in how he's reacted to Shiro mentioning Keith succeeding him. You could assume that it was Keith was showing disbelief because he thought nothing would happen to Shiro, but I think that it may be that he took him very
seriously and didn't know how to handle both the idea of Shiro being gone, or the idea of him being leader.
Out of the three of them, he will probably have the most difficult time, but like with Allura it should lead to some very positive character growth. Keith has always been hot headed and irrational. To be the Black Paladin he's going to have to grow up, and that could be a very fun thing to see.
5: Lotor in General
So, I suspect that we've already seen Lotor in the show. To be exact, Keith and Hunk met him while they were trying to get Scaultrite from the Weblum. That big... planet eating... space worm with poison lasers or whatever Coran called the death beams. My reasoning for thinking this is, when Keith freed him, he noticed that he was Galra, but his outfit was different from other Galra uniforms, enough that it really stood out. And I think I've been justified in that thanks to some released footage that at the very least showed the back of Lotor's head, wearing an outfit like the one seen on the Galra in the Weblum.
But that's not all. I expect that Lotor is half Altean. Some of this was because of classic Lotor's design. Even in that universe he didn't look like any other bad guys. He has more in common with the current version of Alurra. White hair. A more human face. Pointy ears. And from the looks of things he's going to look that way in the current show. Furthermore, in Golion, his mother was more or less a human woman who looked practically identical to Allura. While I expect some of that won't be the case here, I think that Lotor will certainly be half Altean. Which leads me to my next hypothesis.
6: Haggar might be his mother.
I'm not confident on this one. IT could be that Haggar was his mother's sister, or maybe his mother's advisor, but I find the idea of Haggar being his mother to be interesting, and I have exactly one reason for it. Only one. And it's one I didn't notice until my second viewing of Season 2.
Or at least, he comes closer to respecting her than he does anyone else. I know, it's not the same thing as love, but when it comes to matters like this with Zarkon, I don't think this version of him would have children with anyone unless
she commanded at least some of his respect. Love might not even be necessary. Or maybe it was love, either way, out of literally everybody, Haggar is the only
person who has been able to question Zarkon, or point out flaws in his reasoning without suffering some horrible consequence. With other characters, Zarkon may instantly crush them as soon as they offer any form of criticism, or even concern for his safety. With Haggar, Zarkon may not like what he's hearing from her, but at worst he's verbally displeased with her. Haggar is the one who stops herself. Not the other way around. And this is while Zarkon is going on his very self destructive quest to regain control of the black lion. This is when Zarkon is unwilling to listen to anyone.
But it's not both ways. Haggar has shown genuine concern for Zarkon. Such as trying to get him to stop being so obsesses with the black lion, or even her attempts to try to help Zarkon when he was fighting Voltron.
But it's also pretty interesting when you consider that Haggar betrayed her entire species for the sake of Zarkon. Everyone she loved and cared about is now dead. While Haggar certainly is a cruel and evil witch, she also doesn't seem to be cold and emotionless. Perhaps she honestly did fall for him, and her love for Zarkon meant more to her than her love for her people, if she had any at all.