You mean Light Side cards in with Dark Side cards? What they could possibly do if there is a draft format is you are paired with another draftee and one of you gets all of the Light Side cards from both packs and the other player gets all of the Dark Side. Not sure if this will fully make everything "useable" since it looks like certain equipment and support cards only attach to certain types of heroes, which you still might not get.
I'm pretty sure they'll find a way for us to draft though.
There looks to be a decent amount of neutral cards, and most of the common cards are probably neutral (just guessing). If the majority of villain/hero cards are in the rare slot, you may see a situation where everyone just keeps whatever rares they open during the draft, and then choose their side at the end. I don't know, though.
I don't like the idea of splitting light and dark cards because if two people are drafting and you pair them, what if one pulls 4/5 heroes and the other pulls 3/5 heroes? Whoever gets stuck as the villain sort of gets the shaft. That's especially true if all the villains happen to be rares while a few of the heroes are legends. I think people need more ability to choose in a draft setting.