Money is at the core of our problems.
You said it correctly when you stated that humans view things through the economic model.
This kind of thinking is limited and inherently puts us at a disadvantage because we never use latest scientific knowledge or technology, least of all for betterment of everyone.
Instead of looking at things from the perception of monetary economics... eliminate that perception and look at doing things from a technology/resources point of view.
When you do that, the limitations that exist in the monetary based economy, cease to apply, because you no longer apply artificial limitations to what you can do.
Instead you examine what could be done in the most technologically/scientifically efficient/intelligent way.
Life extension is not bad and should be encouraged further...
The point is that our current numbers are nowhere near where its endangering to Earth itself, IF we turned into a sustainable society (and can support much more without impacting the environment in a discernible capacity) - but at the present rate we are doing things, its unsustainable (this much I agree with).
Either way... people are already coming to the realization that the present socio-economic system is not sustainable and its only a matter of time before it eats itself out of existence.
It simply cannot and won't be able to cope with increasing automation technology (its already easier, faster and cheaper, not to mention more efficient to automate a job than it is to wait for a person to get trained/educated to do it - all jobs are based on specialized tasks - and computers surpassed humans in that particular area over 10 years ago).
I seriously have to laugh at those making predictions 100 years from now, when its difficult to do projections 10 to 20 years into the future (seeing how technology and science are racing exponentially, and even within the monetary system, prices of new technology are falling at an increased rate which makes incorporation of the said technology that much faster).