Maybe not literally, but it's not hard to argue we're seeing that practical effect. If a human from a thousand (let alone ten or a hundred thousand) years ago saw his modern (especially Western) descendants he'd probably wonder what epidemic had made them all pallid, hairless and either scrawny or bloated. Most of us would be dead in a week if dropped in the wilderness environments where our forefathers thrived, and most who did survive would do so only because they've been taught how to improvise measures to insulate themselves from it. However great our adaptive ability might once have been, might even remain, we seldom have much environmental impetus to develop it, and so generally don't. Maybe a half century or so of climate controlled enviroments haven't destroyed Westerners adaptive abiltiy, but it has left it fairly stunted from disuse.

Maybe we could, but we're not even supporting a third that number in decent comfort WITH fossil fuels now, so it'll take more than a few blueprints and prototypes (some of which have existed for decades) to convince me they'll ever be more than that. Poverty, disease, hunger and ignorance are still the rule rather than the exception. To the debatable extent that's changing for the 40% of humanity in India and China the rising use of fossil fuels are indispensable. Another billion Africans have been hearing for nearly a century how science was bringing fertilizers, irrigation and mechanization that would turn the continent into a utopian Eden; instead warfare, genocide and disease continue threatening the very existence of whole nations, while even existing and desperately needed generic AIDS drugs remain unavailable. Things are pretty good in Western Europe and North America, though there are definite signs of strain on our existing systems, but elsewhere "decent comfort" is already in rather short supply even with the dubious benefits of fossil fuels.

The idea we will achieve that comfort for three times as many people without those fossil fuels sounds very good, but I see few indications we will even if we can (which is far from certain). Doing so depends on people who desire it but lack the means gaining the access to that means that currently only exists for those who have no desire for it. Western businesses are happy to manufacture the greenhouse homes you mention for anyone who can afford to buy them, bu that's the catch 22: Those who can afford them don't want them, and those who want them can't afford them. The current price of ten barrels of oil is ; the folks for whom that's not much money aren't looking for green tinted tents, and the ones who'd love one don't have $800 lying around waiting for an expense. Meanwhile, the fossil fuels are being depleted and likely altering in radical ways an environment to which we are no longer as skilled at adapting. Not that that's are only risk, of course; as I noted, we could still unleash a nuclear or biological Armageddon at any moment. Your faith in humanitys higher instincts is, to say the least, far greater than mine, but then, if I had much faith in humanitys self improvement I'd probably be Hindu.

Man's not inherently or wholly evil, but he is fallen, and it's important to remember that fact as well as its consequences. One of those consequences is that any idea that starts with "if we just diverted US oil usage" is a non-starter; if doing that were as simple as saying it a major US party wouldn't have been able to make cap and trade a campaign issue. If our achievement of good matched our capacity for good there'd probably be a lot more liberals and people wouldn't be so suspicious of concentrated accumulated power in huuman corporations OR human governments. It's been said that, "Just because that we can do a thing, it does not necessarily follow that we must do that thing" and unfortunately that cuts both ways; the possible and the probable do not always coincide, and in cases where that's regrettable mans moral failings are usually to blame. Setting aside the not insignificant technical challenges to your predictions, you won't convince me mans nobility will overcome his ignobility, because I've seen little evidence to that effect, and much to the contrary. Even when our innovation is motivated by decency or comfort (and the moral virtues of the latter are also debatable) the practical effect tends to be merely efficiency, which is no more inherently good or evil than man or his technology. Even in the industrialized democratic West, do people work less today than they did a hundred years ago, or just differently?

"As long as you can maintain a decent standard of living" is a rather hefty qualifier; again, whether we're able to do that even with the six billion we've got is rather dubious. Before we talk about tripling the population, let alone increasing it orders of magnitude, we should achieve "decent comfort" for the two-thirds of the world without it today; until we do that for at least a majority of six billion promising to do it for a hundred quadrillion is just fantasy, whatever the time frame. IMHO, the best start toward that goal would be recognizing that economy of scale is subject to moral lapses as well as marginal returns and government far from unique in its vulnerability to bureaucracy and arbitrary power abuses of power. Perhaps there's a good reason all politics is local, and perhaps many other things should be equally local for the same very valid reason. I hate to keep playing the political card, but there's a reason for that, too: The only thing that separates government from any other human institution is that, particularly in the democratic West, the public can hold government accountable in ways that simply don't exist for the other institutions. If big government isn't an inherently positive thing even with that accountability, how can any other institution be so without it?