A bigger limit for the successful cases right now is the data limit. Even if silicon wasn't a limit, there's only a good few hundred years of data, and frankly less than 30 years of high volume (if low quality) data. Science as a discipline isn't that old in the grand scheme of things, and the collective data set won't end up training something that can go beyond the input.

It's quite possible "good enough" AI will trap us in a local maximum of mediocrity where the near-term ROI on thinking hard is too low.