It's difficult to say about the future of Bernardo Silva, sometimes Pep Guardiola says the opposite for his players. He is an important player for this club, and we really need him, after a few days the player in question left the club. Maybe Pep is acting like that to maintain the mentality and concentration of other players so they don't get distracted by the transfer market.
I think Man City, especially Pep, will have no trouble if they lose Silva, because there will be many other players they can easily recruit. But in line with what you said, sometimes the adaptation process will be the biggest challenge, especially since the EPL is very competitive every season.
It is difficult to have a replacement that will fit in Sylva's spot because he has contributed a lot to the success of City and his presence do motivate his team. Leaving city is something of his choice and I know that Pep wouldn't hold back any player that choose to leave the club. Pep is a professional coach and Sylva leaving the club wouldn't be a problem for the team as Pep will cover up his spot with other players since the game of City doesn't lie on one player because all the players are superb.
Well Bernardo Silva is a great player for Manchester City, he has a big contribution there. Several players have left Manchester City including one of their important players like Gundogan. Lately I've been hearing a lot of rumors about Silva leaving, so that could be it. But I don't think at all that Guardiola will let Silva go, because we know that he is part of the perfection in the team, he plays very well and can always keep the balance in the midfield with several goal chances for Haaland in every game. I understand that Guardiola is a great coach who can always balance his squad on all fronts, but right now, for Bernardo Silva it doesn't look like he's going to let that go for now. The Premier League is on its way, if he lets him go then at least they need some adaptation time for new players to replace him, and it's not easy.