"You would take, say, $1200 (a very high estimate) and call it a day?"
$1200 what? You're missing a time element there. I assume "per month". I've lived on less than that before, with some comfort, and I was working, too! If I get to assume health care (not unreasonable in the world we're hypothesizing) and don't forget that I'm not working and I'm not worrying about working either, then yeah, that sounds like a pretty good deal for a single guy with no family.
And by the time we kick this into gear, society may well be able to afford more than that. We're not talking today's society (which already has unsustainable levels of social obligation), we're talking a 20-30 year minimum future society. Or at least I am, since I'm actually talking about the real possibility, not a hypothetical parallel universe where it exists today.