[candiodari]

Why? Clearly we have more resources than we need, and a bunch of energy sources we can start to master. If even one of those pans out (and even if it doesn't Nuclear fuel reserves will get us well into 3000 even with exponential growth)

So how do you know your prediction is any different from John Malthus' ? You're assuming quite a lot of efforts will fail. I don't understand how you justify that assumption.

Especially since, if those efforts succeed and we massively increase the energy resources available to the human species, we can trade energy for just about any other resource (including reducing co2, or purifying water, or ...). At that point having hundreds of billions of humans becomes realistic.