It could all turn on Van-El's arrival.
If he were on Earth earlier, he could have saved Ellen and Lucy. He also could have rescued Clark and Lois during the snowstorm, so they wouldn't have been at the cabin at all. Sam would never have been involved with Mindy, so Lois wouldn't have known her at all and wouldn't have followed her in Paris.
I still don't get it, though, because if they are in the correct Universe but the timeline has been altered, why wouldn't they remember the altered past? Everyone else seems to. And if they've been moved to a parallel Universe, how and why? I can't make it work in my head, and I'm looking forward to seeing how you manage to resolve this!
Oh wait, it's Christmas, isn't it? Blame Santa!
