The singer admits the untimely demise of younger superstars like Michael Jackson and Whitney Houston have hit him hard in recent years. He was particularly devastated when Winehouse died of alcohol poisoning as he had envisioned collaborating with her.
Wonder tells Britain's The Guardian, "It's been a heartbreak. Obviously I knew Michael. I knew Whitney, too, and I understand Amy came to my concert in England a couple of years ago. I was thinking about us doing a duet -- an old Marvin [Gaye] and Mary Wells song called 'Once Upon a Time.' It would have been amazing."