Sanchez will be a direct replacement for navas (I know he didn't have lots of starts but he had plenty of game time )and Sanchez will play more then navas did and give us better options for the wide areas ,you can't expect raz and sane to play 60 games a a season.
All top teams have big hitters for lots of positions its what makes you a great team,
One guy is injured or off form you will replace them with another world class player and not a navas or nolito.
Bernardo Silva is not gonna be used in the attacking 3, he is very much a David silva like player who has great ball retention and will play as a free 8 like David and Kevin so it's any 3 of those for 2 positions.
Great position to be in if you ask me