I think the (ideal) future looks more like an accelerated Orion’s Arm, where humanity-changing technologies take over.

Again that’s what I’m getting at. We will never be colonizing Mars as squishy humans… We‘ll be augmented, modified, interfaced with mechanized AI, uploaded, maybe even just mechanical intelligences, something like that. We’ll be using nuclear propulsion, at least. There will be no need to worry about drinking water or breathing oxygen because that will be irrelevant.