I doubt any of that will happen, Zantetsuken.
At least that's what I hope xD
I get kind of pissed when you call it cataclysm..makes me think of another MMO I hate too much..

You know, a moon falling onto a planet could change a lot of stuff!
Maybe it breaks down mountains and stuff so we can explore valleys or whatever was behind it, and that's where some ancient culture had built those ruins.
I'm not a fan of alternative universes and timelines, and using the Echo sounds like a cheap excuse to me.