>As for an impending AI singularity - no one has the first clue what the limits are.

That's simply untrue. Theoretical computer scientists understand the lower bounds limits of many classes of problems. And that for many problems, it's mathematically impossible to significantly improve performance in them with only a linear increase in computing power, regardless of the algorithm/brain/intelligence. Many problems would even not benefit much from a superlinear increase in computing power, because of the nature of exponential growth. For a chaotic system in the mathematical sense, where prediction grows exponentially harder with time, even exactly predicting one minute ahead could require more compute than could be provided by turning the entire known universe into a computer.