Liverpool and Manchester City aren't on the same level this season, while City have struggled for form, Liverpool have been taking the league by storm and still look set to continue, breaking numerous records on the way. And also when City played Norwich, Norwich were in good form then, but that form seem to have faded off as the season went on, so this game is a different game for the both teams.
In general, I agree with your assessment, but you should not forget that you cant go all season (or this very rarely happens) to go on the same level. It seems to me that Liverpool will still experience a period of deterioration of the game, although this, obviously, will not prevent from becoming a champion.