Kyle Walker's future at Manchester City is still being speculated on, I even heard recently that Guardiola himself is still confused about the decision to sell him, it seems that maybe now Guardiola is thinking about keeping him.
Manchester City and Pep Guardiola don't try to keep any player if that one is not very important with them. Looking at how they treated Kyle in latest months of the past season, I don't feel they actually plan to keep Kyle in their club. Firstly he is becoming older and only this contains risk that he will has worse performance for Manchester City in coming seasons. Second Pep and Manchester City just changed their tactics in late of last season and no signal that they will change it back just to help Kyle more comfortable. Except if Kyle adapts to the club new tactics, he will be kept but again his age will be another barrier.
Not having any loyalty to any player may look like that's a bad thing, and it looks like City just doesn't care about any player, but the reality is that if they kept on insisting with the same player for many seasons, they are going to end up with a bad result. So that is why as soon as they start to see a drop in any players talents or skill or even just desire, they end up getting rid of that player and get a better one.
Plus, they are one of the richest clubs in the world, they can spend more money, so if they sell a few players, they can add a lot more on top of it and get a new one. That's a good deal for any team, and no matter who you are, if you can get better players, you will end up doing that if you can.