All of those possibilities can happen this season and now we have seen that Real Madrid will face Manchester City in the play-off round. Many people regret this meeting because it is considered too early for a big match like that to happen in the play-off round. But we all can't do anything because the draw says so. Also as you said, after they play in the play-off round, there are many possibilities for big matches to happen again in the round of 16 later. I mean a match like the meeting between Real Madrid and Manchester City could happen later.
It reminds me of the last Champions League playoffs, when City and Real also met quite early and there was also a lot of talk about how they met too early and that the winner of this pair would eventually become the champion. Obviously, it has always been very difficult to compete with Real, now little has changed, and although it seems that Real is not so strong now, they will always remain the favorites to win the Champions League.