Bernardo doesn't have the sophistication in his play to be a David Silva heir. That's not a knock on Bernardo, but there is a lack of appreciation to just how intelligent David was with his play. He was one of the great Spanish midfielders of the greatest Spanish generation. His movement was unbelievable (when he 1st arrived virtually every MOTD segment was dedicated to his ability to find space in between lines), his reading of the play was outstanding, his ability to control tempo from high up the pitch was almost unmatched in world football, and his creativity was superb too.
Bernardo lacks those things sadly. What Bernardo does have I'd argue, is a better left foot than David. He's a better dribbler, a better shooter, and a better crosser, with an even better 1st touch than David too. And David excelled on all those fronts, which tells you how good Bernardo is. He's got incredibly energy, a brilliant work ethic, is a phenomenal presser and defender, and he still has time to get even better!
They have similarities for sure. Real standout ones too. But really they're different players. Which is ok, because Bernardo is so good in his own way we don't really lose anything from it.
Foden has more potential as a David Silva like-for-like. But then he's so good as a direct attacker he may be moulded differently altogether.
Another thing, Bernardo can play on the wing to a high level. He did it at Monaco, he did it for us in 18/19 plenty of times, and he's done it for Portugal too. I agree he's better centrally, but he's still got potential to be a great asset out wide.