I do not doubt that humans can create superhuman AI, but I don't know how likely self-optimizing AI is.
What appears to be a point against the idea:
While we have proven that very powerful prediction algorithms which can learn to predict these sequences exist, we have also proven that, unfortunately, mathematical analysis cannot be used to discover these algorithms due to problems of Godel incompleteness.
This is from: Is there an Elegant Universal Theory of Prediction?
Lemma 3.3, can have arbitrarily high Kolmogorov complexity but nevertheless can be predicted by trivial algorithms.
This is from your link.
But if it can be predicted by a trivial algorithm, it has LOW Kolmogorov complexity.
Suppose that your current estimate for possibility of an AI takeoff coming in the next 10 years is some probability x. As technology is constantly becoming more sophisticated, presumably your probability estimate 10 years from now will be some y > x. And 10 years after that, it will be z > y. My question is, does there come a point in the future where, assuming that an AI takeoff has not yet happened in spite of much advanced technology, you begin to revise your estimate downward with each passing year? If so, how many decades (centuries) from now would you expect the inflection point in your estimate?