I think they learnt (thankfully) or the info would have been leaked by now...

I really REALLY hope not. Why anyone would want all the story dialogue and every unlockable and secret exposed 2 weeks before the game...is beyond me. There's something to be had when you actually get surprised or experience the story without knowing the big twists and turns already.

I very rarely like surprises of any sort. I like to know it ALL.

I watched a video tutorial by Arturo and he said the demo was actually from a very early build of the game. I wondered why they would do that, then thought maybe to make sure that no extra things are accidentally included like the script from MK9

You'll be surprised. After the MK demo was released, there was tons of leaks based off the script. Some forum member was all like "I have the data, who wants to know the script?" and a shit load of people was like "I do I do", and then he posted it. It was disgusting. I don't understand such mentality, why would you not wait for the game to release to experience the story the way it was supposed to be?

Well, aparently, Lex Luthor knows the Spirit Bomb.

Some of us like to know what our money is getting us before throwing sixty bucks away frivolously, especially when the whole game is a retcon of stuff we might have liked better the first time around.

Injustice isn't MK9 though. Being an Alt Universe story not canon to anything but itself, I'm in no particular hurry to know what happens. Then again, I'm in no particular hurry to own the game period, it's actually turning out to look kinda boring IMO (though this is more of a gameplay and graphics criticism. I've been enjoying the plot in the tie-in comic for what that's worth.)
When the game comes out, I'm just gonna watch the cutscenes on Youtube (which isn't all that different from reading a leaked script, though moving pictures are certainly nicer than text alone), and maybe I'll get the Complete Edition when it comes out, if I haven't forgotten about the game by then.