Re: Scorpion (or others) as DLC
I don't foresee Scorpion, Sub-Zero or any other MK character making it into "Injustice" in any major capacity. This is NRS's chance to branch out away from MK and do something different with an equally beloved set of characters like DC Universe; prove that they are not just about MK.
I think the general public is tired of MK for now and "Injustice" will be a fresh, clean, pure DC Universe experience from NRS. Besides, with the breadth of DC Universe characters to choose from, are guest characters really needed?
From a marketing, money-making standpoint, yes. From a practical, logical standpoint, no. The former always trumps the latter, so I do expect (a) guest character(s), just not from MK even if they aren't needed.