This is one of the things that will weaken Manchester City's performance against Real Madrid and Arsenal in the Premier League and in the UEFA Champions League, respectively. Kyle Walker is a good defender, and if he is not in the Manchester City squad that will face Real Madrid and Arsenal, the Manchester City defense will be vulnerable.
I totally agree with you because irrespective of how good Manchester City is and how they can easily cover up for a player who is injured but with the kind of player Kyle Walker is it will surely affect the performance of Manchester City because in terms of Manchester City defense Kyle Walker is there pillar and also no matter how strong a club is if there defense line is not good all there efforts will go to waste, although Kyle Walker injury is not that bad so he will surely play all there upcoming matches, so that's to say that Manchester City will be using all there full force on there upcoming matches.
I see that the performance of Manchester City players is quite even in all their lines and indeed they have proven that they do not experience a decline in performance when there is player rotation, the same goes for what will happen in the future, it is true that Kyle Walker is quite an influential player but that doesn't mean that if he is absent then the team's performance will decrease drastically.
Manchester City will face 2 difficult matches in the near future, against Arsenal and against Real Madrid and with the problems they are currently facing, many of their players are injured, even though it is difficult, I think Manchester City still has a big chance of getting through these difficult matches victory.
You sound like Manchester City will not lose to Arsenal, even though their first eleven are all injured. The Arsenal of this season is different from the Arsenal of last season, and they won against Manchester City at the Emirate Stadium this season. Arsenal is consistent and scores a lot of goals against their opponents. Arsenal is capable of beating Manchester City on Sunday.