Failure is not an option for Grealish or City, that must be the reality.
Can't afford to lose a world class player like Bernie without getting someone of a similar grade.
I do think many people underestimate the intensity and creativity someone like Neymar could bring, if you put him in the ten he would probably assist as many as Kev.
If you put him out wide, Grealish or Phil can move inside?
My only concern would be the person dropping deeper to help the base of the midfield out?
The only thing that makes Bernardo irreplaceable is our "build ups" against the bigger teams.. Even yesterday, there were times when Bernardo would go deeper to his beloved RCM role and make our build up play smoother. Otherwise we struggled.. This happens all the time, except against the teams - that defend the box with 11 players and think about counter attacks. Aston Villa game for example, Bernardo was completely useless there and Gundo for example - showed his worth in that game.. So it depends, but in 90% of the games, you need Bernardo as there are away games, teams like Newcastle or Leicester who want to possess the ball and number of so called "Jose Mourinho bus" teams is becoming shorter and shorter..
Except Rodri (and we haven't seen Phillips yet..), every our midfield player struggles during the high pressing and we have seen it throughout the many seasons.. 2017 / 2018 team was great but against Liverpool high-press they were destroyed and this only changed when Pep introduced Bernardo in midfield since 2018 / 2019 season and that happened due to KDB's injury, otherwise it wouldn't, but that's the history now..
So, Bernardo helps us - to cope with the high press and does this - via his exceptional ball-controlling and dribbling skills. Apart from that he isn't irreplaceable I guess.. Gundo is better in the box, KDB of course and Phillips can be as good as Bernardo is in defending I'm sure, but there isn't anyone in the team - who would dribble across our box with the ball and destroy opponent's high pressing..
But we have options in Grealish and Foden..
Jack has similar ball-control and dribbling skills and why not - if Pep gives him time - I'm sure soon Jack will be great there.. People here mentioned David Silva and it's true, he wasn't great defender either and not as good against high press as Bernardo is - but he played is best football in midfield, rather than on the wing during Mancini or Pellegrini era..
And Foden of course.. Actually Phil is my favorite to replace Bernardo if needed.. Phil runs a lot, defends a lot, can dribble, can control the ball, remember that cross to Grealish in FA cup ? We don't need to look further, just give Foden some chance (it's funny Pep introduced him as LCM for the first time in CL final.. stupid decision :D) and he will do great job..
And TBH - we all know, Foden is too good to be limited for a wide winger role... Just remembered how his effort against Atletico - helped us to go to the next stage..
So if Bernardo is gone, we have plenty of options: 1) Foden 2) Grealish and maybe sign another LW to cover Grealish.. But honestly I would give more minutes to Palmer / Alvarez / Kayky..
Problem is - if we replace Bernardo with Gundo or Phillips.. They can be great players, but against Liverpool for example - we will struggle to make good build ups...