I look forward to a future where most of the economy is optional and I can walk away from it and retire in complete comfort. Hint, we're getting there and if you're not building real wealth you're going to miss it and be FORCED to play video games to pay me rent on the physical world you take up space in.

Buying Photoshop instead of using GIMP or Abercrombie instead of George consumes little or no more real resources, but by any regular measure of economic growth it's an increase in real output if people switch. Same applies to people buying shiny new Teslas that consume less real resources than the low-end Ford they used to drive. Or indeed, as I hinted I suspect will increasingly be the case in future, people spending sizeable proportions of their income on cures for chronic ailments that take an relatively trivial amount of energy to implement. Economic growth is fundamentally not measured in units of energy.

For my relaxing woodworking hobby I have a midrange table saw. In eternal economic growth I could improve my hobby by buying a much better saw, a giant cast iron table beast with 2 HP motor and a kilobuck fence system and kilobuck dust extraction (instead of my cheap hundred buck system) maybe given infinite money something better than current top of the line, or better than can currently be imagined, could be sold to me. Fundamentally there is a limit of the theoretical best imaginable table saw. At that point economic growth ceases. This also happens with cars and houses. It does not appear possible to design and build a car that is road legal better than a couple million dollars, given income inequality we should be able to charge $25M for a super car and there would be plenty of sales at that level, but engineers can't find a way to spend that much even on custom cars.

But you argue the perfect table saw could be value engineered to fail often. OK then, you bought yourself a couple more orders of magnitude of economic growth but still hit physical limits. Now I replace my saw every time I use it, heck, every cut I make. Eventually there comes a fundamental physical limit to how many boxed saws I can slide down my basement stairs. So you implement drone delivery of table saws. OK then we run into a limitation of living in a 3-d universe, where the lifespan of my table saws are so small I can't deliver them fast enough to make money producing more of them, and the waste heat is so high my skin burns.

Now at those fundamental physical limits, how do we increase economic activity?

There is another fundamental physical limit based on income inequality. If you take total income or wealth across the country and divide it equally, perhaps everyone in the USA could buy a table saw like mine, today, which sounds awesome, because fine carpentry is fun as an art form, etc. However we concentrate all our income and wealth at the top. And none of us (statistically) are at the top. Eventually like the last days of the Roman Republic we'll have all the wealth owned by one dude. And if Dude doesn't like carpentry as a hobby, and no one else can afford even the cheapest of table saws, then Dude can increase his income and wealth into perpetuity but table saw sales will drop to zero permanently, even if the plan was to eternally sustain economic growth by making and selling table saws. This is our medium term future. The economic problem with income inequality or our current return to feudalism is that the one dude at the top can't spend money fast enough or wisely enough to keep the economy alive, much less eternally growing. And if a detailed analysis of economic conditions shows that for a couple generations all we've been doing is transferring wealth upwards to the rich rather than actually being productive, then obviously that has to stop once there is no more wealth to extract from the peasants, even if for a couple decades, reports of economic activity look very busy. Its like pumping oil out of a well and thinking the well is bottomless, for a little while you can "create" oil and oil wealth out of nothingness, but eventually you run into a problem with that business model once the cheap oil is all pumped out.

Economic activity is just a way to keep score in the competition to use energy and resources ever faster, well, ever faster until it isn't anymore.

The question is what you can do with the saw. As you note, fine carpentry is an art form. There's no limit to the possible value of the art you could produce with the saw and other tools. There's no limit to the possible total value of the art that could exist in the world.

A finite earth can support a finite population which can use finite resources to employ a finite economy. I'm not sure what's difficult about that concept; especially since a zero-growth economy is not a new concept (it's called 'maturity' when applied to an ecological system).

You're also overlooking the rather obvious and important fact that the quality of different works varies tremendously. While it's true that appreciating art does require some time, the amount of value I receive in return, and therefore the price I'm willing to pay, is a function of (my perception of) the quality of the work. And it doesn't necessarily take me more time to experience a higher-quality work than a lower-quality one.

I think it's pretty ludicrous to suggest we'll reach the limits of the growth potential of human [conspicuous] consumption at any time in the foreseeable future, and frankly if it starts to look like a serious problem any time in the next five or so centuries we might even have enough disposable income to pool to create a non-debt/inflation based financing system so we don't lose all our savings. Assuming we still care about our savings. :-)

I actually think the tendency of wealth to concentrate which you've also mentioned is a bigger problem, but we already have large-scale direct and indirect redistribution of incomes and I don't see future electorates voting for the party that lets the [competent] descendants of todays' billionaires continue to accumulate all the wealth.

And after patent expiration, many of those technologies could become very cheap - because they are either dealing with information(i.e. labs on chip) which generally has moore's law like economics, or dealing with giving minute quantities of materials to people - and making that is either very cheap today - or synthetic biology would probably make it very cheap.

So i'm not sure healthcare will be a growth engine.But maybe living to 150 or forever will offer a lot of growth.