While I would certainly expect a radical change to economics even from a middling IQ AI — or indeed a low IQ, as I have previously used the example of IQ 85 because that's 15.9% of the population that would become permanently unable to be economically useful — I don't think it's quite as you say.
Increasing IQ scores seem to allow increasingly difficult tasks to be performed competently — not just the same tasks faster, and also not just "increasingly difficult" in the big-O-notation sense, but it seems like below certain IQ thresholds (or above them but with certain pathologies), some thoughts just aren't "thinkable" even with unbounded time.
While this might simply be an illusion that breaks with computers because silicon outpaces synapses by literally the degree to which jogging outpaces continental drift, I don't see strong evidence at this time for the idea that this is an illusion. We may get that evidence in a very short window, but I don't see it yet.
Therefore, in the absence of full brain uploads, I suspect that higher IQ people may well be able to perform useful work even as lower IQ people are outclassed by AI.
If we do get full brain uploads, then it's the other way around, as a few super-geniuses will get their brains scanned but say it takes a billion dollars a year to run the sim in real time, then Moore's and Koomey's laws will take n years to lower that to $10 million dollars a year, 2n years to lower it to a $100k a year, and 3n years to lower it to $1k/year.
