There's no good definition of superintelligence. A calculator is already way more capable than any human at doing simple mathematical operations, and even small AIs for local use can instantly recall all sorts of impressive knowledge about virtually any field of study, which would be unfeasible for any human; but neither of those is what people mean when they wonder whether future AIs will have superintelligence.

> But it's far from clear that we're not moving toward a plateau in what these agents can do.

It is a debatable topic, and I agree with you that it's unclear whether we will hit the wall or not at some point. But one point I want to mention is that at the time when the AI agents were only conceived and the most popular type of """AI""" was LLM-based chatbot, it also seemed that we're approaching some kind of plateau in their performance. Then "agents" appeared, and this plateau, the wall we're likely to hit at some point, the boundary was pushed further. I don't know (who knows at all?) how far away we can push the boundaries, but who knows what comes next? Who knows, for example, when a completely new architecture different from Transformers will come out and be adopted everywhere, which will allow for something new? Future is uncertain. We may hit the wall this year, or we may not hit it in the next 10-20 years. It is, indeed, unclear.