"But here's the thing. Once technology jumps over a hurdle thought impassable before, it makes that supposed miracle utterly commonplace and boring."

Agreed. Brin's 'Glory Season' might be more realistic in that respect.

But where's the optimism part...?

Um, probably 'Metropolis...'

If there's a better explanation for a human space migration/diaspora to save our species from single-point extinction than yours, I haven't heard it...

Hell, I just know it's a story I wish I'd written...

Hmm. Presumably being vaporized quickly (arguably a form of disassembly, itself), as opposed to being broken down at a speed that I can feel. Unless they're explicitly programmed to shut down my nervous system as they go, I have to think that molecular nanobots disassembling me, might feel like dissolving in acid...

I have a rough memory of a short story about the pilot of the first FTL ship who destroys it immediately after returning, after finding a planet something like that...

"Where's the record breaking 70 foot speedboat jump over a cop car? "

"(Remember companies that develop treatments want to make as much as possible) "

Ah, okay. That makes somewhat more sense. Given only the second line, I could only conclude it was a 'fairness' argument. I've seen similar arguments on other things before...

"Oh, bother." said Pooh, as he stopped to reload...

"Everybody would live forever, leading to overpopulation."

"Is anyone else getting tired of life extension always being presented as a horror show of some sort? Why must this be?"

Actually, I've wondered what it would be like if you already had a major forest fire happening (in, say, Texas), and a hurricane comes barreling ashore right at it.

And I still have visions of that submerged, leaking gas main in New Orleans, where the gas was burning once it emerged from the water...

"My problem is that I start working on a project, finish chapter one, and decide I'm not happy with it. So I revise it, and then I revise it again, and again, and again, and then I rewrite it, and revise it, and so on, ad infinitum. "

CSI:Cetacea...

But when all else fails...

My problem with the Terminator Universe* is: Suppose you're Skynet. You send a Terminator back to kill John. It succeeds.