Kokipy wrote:

Didn’t Asimov do it also in the end? I seem to remember he linked the robot books with some other story arc which had been unrelated up to that point. It was unsatisfying. Kind of, perhaps, related to how some felt when Rey turns out to be the emperor’s granddaughter. Ultimately this feels like a failure of imagination. 

I believe he ended the Foundation arc with finding R. Daneel Olivaw in a very poor state.