News says that Torchwood is coming back for a season four, but last I checked there was no word on casting.

I must say that Children of Earth left me cold - but that's mainly because that's how I react when I've been dropped out of the reality by sucky story-telling/plot hole; then any attempt at emotional resonance is going to feel exactly like the manipulation you've talked about, and I'll be digging my heels in, and refusing to be played.