I would have thought that is obvious. Chain of thought is clearly the right path forwards. People don't stare at a thing and immediately come to a solution. Without chain of thought, you are mostly dealing with a statistical regurgitation machine. Effective for some tasks yes, but clearly not enough to meet the bar of general intelligence.

I think you are wrong that this is the limit for single shot though. We have reached a limit due to data, but I expect what will happen next is that we will transition into a slow growth phase where chain of thought models will be used to effectively create more training data, which will then be used to train a better single shot model, which will then be extended into a better chain of thought model, which will then produce higher quality training data for another single shot. And so on. Kind of like what happens as knowledge passes from teacher to student across successive generations. Effectively a continuing process of compression and growth in intelligence, but progressing rather slowly compared to what we have seen in the last 5 years.