askchapo

Basically yes, however the differences would be massive. The only relatively current estimates & modeling I've found for this come from the book Half Earth Socialism. Some highlights I recall, under both energy & land use constraints:

• Essentially zero air travel
• Nearly 100% mandatory veganism
• Nobody uses private cars to commute
• You are limited to about 48 kWh of energy usage/day, or about 2000 W average at any given time. A single AC unit would pretty much entirely consume this energy budget. Currently USians use 12,000 W average at any given time. Your monster gaming PC would be illegal, sorry.

There are some tradeoffs that could be made (you occasionally get to eat meat but have to use 1500 W instead of 2000 W, etc.) but land use is the big fundamental constraint if you want to avoid xenociding 85% of the world's species (so you need to set aside half the earth for them). I know we all like those photos of mountains covered in solar panels in China but that's an example of land use devoted to electricity.

The big wildcard here is nuclear power. I don't want to start a nuclear power argument because those go nowhere. The Half Earth book doesn't use nuclear in its scenarios because the largest base of support for eco policies is anti-nuclear. Whether you view overcoming that resistance as more or less realistic than convincing USian treatlerites to give up borger is of course up to you.

There is also the question of how in a society free from want you get people to do jobs that really fucking suck. This is in the "fun to speculate about" wheelhouse. Obviously capitalism takes the stick approach and threatens the global south with homelessness, starvation, and even direct murder if they don't do the shitty jobs. Transforming this into a pure carrot-based approach is the domain of speculative fiction like The Dispossessed.

Jason Hickel is promoting a study that says we are about 300% past post scarcity

This was Buckminster Fuller's big thesis, that if all the military and police budgets were dedicated to human needs then we could live in a mostly post-scarcity world, and he was saying this confidently in the 60s. But in reality, the Soviet Union had already proven it in practice at least a decade earlier. Maybe it was even possible long before then.

I'm way out on the fringe, I say that the technological threshold for meeting these needs is the glass pane and lens. If you let people get to know their land and diversify their agricultural production as they please instead of producing as tribute or as global commodities, there's a lot they can do. If you can share as much as possible and coordinate things on the appropriate scale (block, municipality, region), and have a modular and transparent process for repairing and recycling components, then you really only need a small fraction of the industrial capacity we have today.

Ever since the early 20th century, Western economies have been characterized by overproduction and surplus physical capital that led to the paradigms of consumerism, marketing, landfills, and overseas wars, all to dispose of that surplus and maintain a perennial direction of growth in the markets. It's a testament to the ideology of capitalism that once we figure out how to do a given action with a higher energy intensity, we forget that it was possible to do it with less energy. The obsession with "raising the productive capacities", without a clear vision of what the goal capacity is, speaks to being beholden to this ideology. It just becomes infinite growth under a different lexicon. Your first 2 bullet points are reasonably specific, but the remaining 5 are quite vague, subjective, or debateable.

Think about it, what is the set of human needs, and what does it take to fulfil them without deprivation? Do you really need to buy 8 new outfits a year, or is 10-15 outfits enough to tide you over for 15 years until they're all worn out? Do you really need to get a new car every year, or can you use a car for 300 hours a year in such a way that you share N cars amongst 6N people? Do you need a smartphone every 2 years, or could you stretch it out to 5 years, or go without a smartphone and just use a PC, or even just go to a computer lab a few times a day? Do you really need to eat meat at every meal, or would you be satisfied and healthier with alternatives that have 1/20 of the embodied energy that red meat does? Do you really need a fourth of a hectare of private space, or do you just need 40 square meters of private space (with enough sound insulation) and then just access to all the places that are freed from jealous individual ownership? Do you really need 15 kWh of electricity a day to heat your dwelling, or would 2 kg of wood in a masonry heater be enough? Do you really need your own kitchen and shower, or do you just need these within a 3-minute distance? Do you really need your own toilet in a 10-meter radius that needs a water column of 50 meters to supply with water just to flush your human waste out into the waterways, or would you be okay with a composting toilet in 1 minute walking distance that never clogs, never leaks, doesn't stink, and provides fertilizer for orchards? We need the advances of modern medicine, but with a decent diet and lifestyle, would we really need quite so much of them as to make up 18% of GDP, or would we be able to keep everybody well with just 5% of GDP and universal health care?

If you picked the thrifty answer to all these questions and applied that to everyone, you'd easily cut land use and energy generation and industrial production and required labor by about 80%, and that would put you well beneath the level of planetary overshoot. This is what we mean when we say that degrowth is necessary and would not harm humanity in the slightest.

Editing in what I forgot: The implication here is that we waste and want in order to consume about 5x as much as we need. There is a coefficient of redundancy, or unnecessary replacement, in our economy and that coefficient is probably 3 at the very least.

Primitive communism was able to provide for most people's needs, there were just a few gaps that were unpleasant but did not cause widespread immiseration. It was stamped out because it was not able to militarily contend with the slave mode of production of developing states. With enough coordination and a collapse of the states' cohesion, the long-abandoned lifeways could open up again. Appropriate technology could provide all we need. A bold assertion is that eyeglasses and the printing press would be enough. A cautious assertion is that a slimmed-down tech tree leading up to a circuit board would be enough.