As to Kerrigan... well, I don't know if we'll still have her for Heart of the Swarm, obviously they couldn't just come out and say that Kerrigan would no longer be leading the Swarm, that would have been a massive spoiler.

Then again, there aren't really any other known Zerg characters left - Kerrigan killed Daggoth and the last Cerebrates offscreen, the Overmind is dead...

So you might be right, though I should hope not - that would leave us with either 'Kerrigan is still evil and everything we've been through in Wings of Liberty was essentially futile' or 'the Zerg are good now' which not only reeks of the Orc retcon win WarCraft and a horrible 'everyone allies against the Hybrids' climax, but it would also ruin the Zerg's villainous flavour - already somewhat troubled by the Overmind's motives being retconned into being implanted by the Voice in the Darkness rather than its own goal of evolutionary perfection.