Yeah, teams like Real leave themselves open, because they trust themselves to either control or be good enough to win the game. They don't leave themselves open like City do though. City are like Arsenal at times...the opposition get the ball, play two easy passes and suddenly City's centrebacks are exposed and one of them is inexplicably lying on the floor. You just can't be that easy to cut through against the top sides. It doesn't matter how good you are against the not quite top ones. When City play Real, or Barcelona, or PSG, at the business end of the season, they wont be able to keep the ball off them enough to stop them from playing, and if they can't do that, they will lose.
Based on the weekend I would say they'd be pushing their luck massively even against a United side on a good day, and United are nowhere near the level of teams you could meet in the CL quarter or semi finals.
I don't think there is a set way of playing for success. People seme to like banging on about teams and their identity, but teams generally play how the manager sets them up to play. You can win Champions Leagues playing exapnsive possession football...or you can win them playing compact counter attacking football. Or you can win them because Barcelona and Bayern Munich somehow contrive to miss about 500 easy chances in a row against you.
I think part of the reason we have so many teams play "boring" football in England is because there is just too much on the line. Being in the PL is really lucrative, to the point dropping out of it is a massive disaster, and there's more competitive teams than there are spaces in the PL for them. Teams can't really afford to be playing open, expressive football and risk not being competitive, when they can timewaste their way to a 0-0. Or even if they cn riskk being more expansive, often aren't brave enough to.
I can certainly see English teams closing the gap, because, in recent years, it's been hard to pick out where the improvement has been cming form in the PL. One year someone wins it, the next, they end up finishing midtable and another team who are no better than them win it in their place. This year, City are much better than anyone was last year. Chelsea I would say are little or no worse, United are better, Liverpool are better. There is visible improvement, which means the bar raises for anyone wishing to compete at the top end. Already this year whoever wins it (City) will be a better team than any PL winning side in about 5-6 years. Whoever finishes second will probably have to be better than any team who's won it in the last 3-4.