Not suggesting I am a managerial savant, but I think most can agree that doing what Everton and Chelsea did in sitting back and not having an option to counter is entirely unproductive and will only result in one outcome. Not engaging this team at all is NOT the answer. It never has been against a Guardiola side. At the very least you can stick a boot in, rouse the home crowd and reduce the amount of time each City player has to think. It's a cheap, cynical tactic but one that can prove profitable. Because letting any Guardiola team operate in serenity is a recipe for disaster.
The domestic and European teams that have enjoyed the most success against Pep's Barca, Bayern and City are the ones who can either effectively deny space and then use the ball efficiently on the counter or be brave, ruffle some feathers and attack Pep's defence in numbers. Pressing a la Spurs or Liverpool is undeniably hard to emulate, but everything else can be achieved through sheer hard work and belief.
You're implying that there isn't a way to beat this City team - which is precisely the problem. Too many managers share your defeatism. So many teams take to the field with City with a defeatist attitude. That is precisely what Guardiola wants. Because it makes his and his teams job much easier. Ferguson used Old Trafford to his advantage in the same manner, teams would turn up fearing the worst and go on to lose 3-0.
Sitting back, accepting your fate and not having a plan as to how to score is a cowardly approach. I'm not denying that are an exceptional team, but every team is beatable, even one managed by Pep Guardiola. Opposition simply aren't doing enough to unnerve City and to plant doubt. That only serves to embolden them. Confidence is a wonderful thing in football and City have a bucketful of it - until someone or something is brave enough to bring them down a peg or two, the pattern for upcoming seasons will be set.
Anyone who has watched football for long enough recognises the conditions in which certain teams and managers like to operate. It doesn't take a genius to work out that upsetting those conditions will give you a greater chance of success.