Quantity vs quality, in this case, is a false dichotomy. Curves of scientific-technological developments measured by, for example, patent filings over the centuries, track global population size. The reason for this is that the larger the population, the more people with talent for scientific and technological research are born, the more means they have to dedicate themselves to such pursuits due to economies of scale, and the larger the pool of extremely high-IQ individuals within this subset of the population who're responsible for the discoveries with the highest impact, all due to the long tails of the different normal distributions associated with these traits. Any downward change to these parameters will result in a slowdown of discoveries, which will in turn will result in a reduction in technological development, which in turn will result in economic stagnation, producing a vicious spiral.
There are, evidently, other factors involved, such as political and economic models that favor or hinder such developments. But these, too, are a factor of population size. A shrinking population results in disproportionately large pressure, by those who want to maintain their standard of living, in favor of strong policies enforcing the short-term status quo for themselves, with disregard for long-term effects, see e.g. Japan and South Korea. This kind of status quo-maintaining effort is almost invariably detrimental to novel scientific research, since it favors, at best, iterative improvement of what's already well-known, not actual novelty. So the problem is compounded.
The world may still manage to find an alternative model for producing a long tail of high-IQ individuals with the means to continue generating exponentially growing novelty research, but, right now, no such model exists, and expecting one to arise just because, out of the blue, over the next few decades, is part of the wishful thinking mentality I referred to before.