I predicted Berrettini to win Wimbledon because I just felt change in the air, but did I really think Berrettini would win? Wistful thinking at most.
But, I really believe that Djokovic is not winning the USO, and for several reasons: There are many more threats at the USO, he's always struggled at the USO, and the pressure of winning both the CYGS and #21 will add to his struggles at the USO.
And, I think the tennis gods wanted 20-20-20 all along. They won't allow Djokovic, Nadal, or Federer to win #21.