I agree. And I struggle to imagine a Civ approach that will help the City States feel alive. Whether it's throwing gold at City States or completing disjointed quests for envoys, I can't see the process of gaining suzerainship over City States becoming interesting under mechanisms.
I hope I'm wrong and the development team comes up some good ideas (well executed) to breathe life into the diplomacy game.
Going back to ideas I expressed before about changing the various victory conditions into an integrated system where you gain recognition from other civs that you are the world leader, a similar approach could be applied to City States. That is, they could follow you if you have sufficient influence in a variety of categories (military dominance, economic influence, cultural influence, religious influence, scientific prowess, etc.) and more such categories than any other civ. Maybe that could lead to a diplomatic game that ties all the other game mechanics together into a multi-faceted battle for control over the minds of City States.