Ed did pluralize when he said 'descendants', didn't he? Seems Sonya and Johnny aren't the only ones who knocked boots. Thought I'd draw up a list of other likely candidates that could spawn new characters:


Reptile and Khameleon:

I'd call this the most likely of scenarios; at this point I'm kind of convinced it's happened due to the Saurian corpses we can see in the dock level.
Seems to me that the alternate timeline has been very kind to him, and he and Khameleon finally got the job done. They were fruitful and multiplied...and multiplied.

...of course, with Reptile's luck we'll find out matriarch Saurians eat their mates after the deed is done or something equally awful, but I digress.

Baraka and Mileena:

Well, with Kahn and Kitana dead, this more or less makes Mileena the rightful heir to the Outworld throne, doesn't it? Wouldn't surprise me to find out that she and Baraka had a kid of their own about now. A horrible toothed baby playing with blocks around the Outworld throne. Bet Shang would have made a wonderful nanny if he were still around.

Cyber-ninjas:

Not actual reproduction per se, but it would make sense in the intervening years for Sektor/the Lin Kuei/Tekunin to develop advancements in cyber-technology. We could be looking at a new type of cyborg. Then again, I tend to think Sektor would perform said modifications, if any, on himself.

Shokans:

We have a few possibilities, don't we? Goro does have seven wives, after all. Maybe Kintaro got lucky and we'll have an oppressed tiger-striped minority ready to take on his race's cause? I think we're kind of overdue for a fresh new Shokan.

Others?