I think the Sub-Zero in this trailer is the older brother. They're just rehashing the old occurrence where Scorpion kills Sub-Zero once again (they can stop doing that now, btw. i think it was handled pretty well in MK9).

I think of this trailer as a flash-back of sorts. "Yes, they fought, and this is where we were left off at between these two: Scorpion kills Sub-Zero"

With that said, I think we'll see the younger brother alot more active in MKX. I think he'll don his elder brothers garmets like they had him do in MK9, but I think we'll not only get to see the older brother transform and emerge as Noob, but we'll get to see the younger brother emerge and transform into the new leader of the Lin Kuei.

The transitions he made from MK4 through and into MKDA and or MKD. I think there's enough story line there to allow this idea of alternates to happen without forcing or becoming too strange or overtly "new on purpose."

The main reason why Human Sub-Zero is back in the trailer is simply due to the fact that the game would not be intriguing to a casual MK fan that missed MK9 and saw Scorpion fighting a blue robot. It just wouldn't get people talking like it did. However, my prediction for story purposes is that the Lin Kuei recovered the body of Cyber Sub Zero, they reboot his system and he comes back online. He somehow gets his humanity back (fill in the blank) however, he is still not human as they are unable to replace his organs, hence the glowing eyes. In shorter terms...Sub Zero in MKX is Kuai Lang.

I have two possible theories on why Human Sub is back.

1. It is Kuai brought back from the dead by Quan Chi and Shinnok to serve the forces of the Netherealm. Maybe they restore him to his original body or put his soul into a new one.

or

2. This new Sub-Zero is Bi Han and Kuai Liang's father. Their father was a Human Cryomancer. Maybe he is trying to avenge both his sons' deaths.

Theory 1 is probably the route NRS is taking, but this new Sub-Zero being their father would explain why Sub looks older and has the bluish skin and blue eyes in the trailer.

I'm starting to get worried about story in general. Boon's comment saying it is a continuation and it isn't worries me.

I'm really starting to think it will be a time travel storyline. Especially with this mention of different iterations of characters.

I HATE Bi-Han as Sub-Zero. Mostly because I think his attitude is so much more fitting of Noob Saibot.

I will say one theory I'm tired of hearing though. The theory that Bi-Han gets split from Noob Saibot in the soulnado would be an abomination to the story for me. Noob Saibot is supposed to BE Bi-Han so there should be no separating. Also, taking Scorpion's story and placing it on him would be lazy and boring all at the same time. Not to mention the Gods should HATE Bi-Han. Mythologies fans know he murdered gods. Just sayin, this is a bad story and if Bi-Han becomes Sub-Zero that way then I just give up on story. Mk would be strictly for gameplay at that point.

I think it is Kuai Lang because Boon won't kill Noob.

My guess is it is the past Sub-Zero brought to the future by Raiden..

All this talk of "Multiple Versions" of characters... I've already posted this but Im betting since 90% of Earth's warriors are dead, Raiden will be going into the past to recruit younger versions of them...

Just like Beast in the current XMen comics.

I think this is a new Sub-Zero and not the brothers. He looks more mysterious and darker so I hoping he is all-new.

It's fun to see some Sub-Zero fans STILL whining about CSZ and it was three years ago. It's twice fun to see some of them vehemently hating Bi-Han as Sub-Zero. Yeah, sure for the casual player it SO meaningful who is behind the mask. And generally, if storyline benefits from Bi-Han returning as SZ, It's better this way. Personally, I think it will be fun, if NRS once again did something bad to Kuai Liang. I guess, some people here will implode. Ha-ha.

But really, in case of the trailer, I'd say, it's just a promo made to be recognizable - nothing to make conclusions from.

I mean Bi-Han works better as Noob Saibot anyway and if Bi-Han is Sub-Zero than why even make him Noob in the first place.